path: root/sql/ha_partition.cc

/*
  Copyright (c) 2005, 2012, Oracle and/or its affiliates.

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; version 2 of the License.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

/*
  This handler was developed by Mikael Ronstrom for version 5.1 of MySQL.
  It is an abstraction layer on top of other handlers such as MyISAM,
  InnoDB, Federated, Berkeley DB and so forth. Partitioned tables can also
  be handled by a storage engine. The current example of this is NDB
  Cluster that has internally handled partitioning. This have benefits in
  that many loops needed in the partition handler can be avoided.

  Partitioning has an inherent feature which in some cases is positive and
  in some cases is negative. It splits the data into chunks. This makes
  the data more manageable, queries can easily be parallelised towards the
  parts and indexes are split such that there are less levels in the
  index trees. The inherent disadvantage is that to use a split index
  one has to scan all index parts which is ok for large queries but for
  small queries it can be a disadvantage.

  Partitioning lays the foundation for more manageable databases that are
  extremely large. It does also lay the foundation for more parallelism
  in the execution of queries. This functionality will grow with later
  versions of MySQL.

  You can enable it in your buld by doing the following during your build
  process:
  ./configure --with-partition

  The partition is setup to use table locks. It implements an partition "SHARE"
  that is inserted into a hash by table name. You can use this to store
  information of state that any partition handler object will be able to see
  if it is using the same table.

  Please read the object definition in ha_partition.h before reading the rest
  if this file.
*/

#ifdef __GNUC__
#pragma implementation				// gcc: Class implementation
#endif

#include "mysql_priv.h"

#ifdef WITH_PARTITION_STORAGE_ENGINE
#include "ha_partition.h"

#include <mysql/plugin.h>

#include "debug_sync.h"

static const char *ha_par_ext= ".par";
#ifdef NOT_USED
static int free_share(PARTITION_SHARE * share);
static PARTITION_SHARE *get_share(const char *table_name, TABLE * table);
#endif

/****************************************************************************
                MODULE create/delete handler object
****************************************************************************/

static handler *partition_create_handler(handlerton *hton,
                                         TABLE_SHARE *share,
                                         MEM_ROOT *mem_root);
static uint partition_flags();
static uint alter_table_flags(uint flags);


static int partition_initialize(void *p)
{

  handlerton *partition_hton;
  partition_hton= (handlerton *)p;

  partition_hton->state= SHOW_OPTION_YES;
  partition_hton->db_type= DB_TYPE_PARTITION_DB;
  partition_hton->create= partition_create_handler;
  partition_hton->partition_flags= partition_flags;
  partition_hton->alter_table_flags= alter_table_flags;
  partition_hton->flags= HTON_NOT_USER_SELECTABLE |
                         HTON_HIDDEN |
                         HTON_TEMPORARY_NOT_SUPPORTED;

  return 0;
}

/*
  Create new partition handler

  SYNOPSIS
    partition_create_handler()
    table                       Table object

  RETURN VALUE
    New partition object
*/

static handler *partition_create_handler(handlerton *hton, 
                                         TABLE_SHARE *share,
                                         MEM_ROOT *mem_root)
{
  ha_partition *file= new (mem_root) ha_partition(hton, share);
  if (file && file->initialize_partition(mem_root))
  {
    delete file;
    file= 0;
  }
  return file;
}

/*
  HA_CAN_PARTITION:
  Used by storage engines that can handle partitioning without this
  partition handler
  (Partition, NDB)

  HA_CAN_UPDATE_PARTITION_KEY:
  Set if the handler can update fields that are part of the partition
  function.

  HA_CAN_PARTITION_UNIQUE:
  Set if the handler can handle unique indexes where the fields of the
  unique key are not part of the fields of the partition function. Thus
  a unique key can be set on all fields.

  HA_USE_AUTO_PARTITION
  Set if the handler sets all tables to be partitioned by default.
*/

static uint partition_flags()
{
  return HA_CAN_PARTITION;
}

static uint alter_table_flags(uint flags __attribute__((unused)))
{
  return (HA_PARTITION_FUNCTION_SUPPORTED |
          HA_FAST_CHANGE_PARTITION);
}

const uint ha_partition::NO_CURRENT_PART_ID= 0xFFFFFFFF;

/*
  Constructor method

  SYNOPSIS
    ha_partition()
    table                       Table object

  RETURN VALUE
    NONE
*/

ha_partition::ha_partition(handlerton *hton, TABLE_SHARE *share)
  :handler(hton, share)
{
  DBUG_ENTER("ha_partition::ha_partition(table)");
  init_alloc_root(&m_mem_root, 512, 512);
  init_handler_variables();
  DBUG_VOID_RETURN;
}


/*
  Constructor method

  SYNOPSIS
    ha_partition()
    part_info                       Partition info

  RETURN VALUE
    NONE
*/

ha_partition::ha_partition(handlerton *hton, partition_info *part_info)
  :handler(hton, NULL)
{
  DBUG_ENTER("ha_partition::ha_partition(part_info)");
  DBUG_ASSERT(part_info);
  init_alloc_root(&m_mem_root, 512, 512);
  init_handler_variables();
  m_part_info= part_info;
  m_create_handler= TRUE;
  m_is_sub_partitioned= m_part_info->is_sub_partitioned();
  DBUG_VOID_RETURN;
}

/**
  ha_partition constructor method used by ha_partition::clone()

  @param hton               Handlerton (partition_hton)
  @param share              Table share object
  @param part_info_arg      partition_info to use
  @param clone_arg          ha_partition to clone
  @param clme_mem_root_arg  MEM_ROOT to use

  @return New partition handler
*/

ha_partition::ha_partition(handlerton *hton, TABLE_SHARE *share,
                           partition_info *part_info_arg,
                           ha_partition *clone_arg,
                           MEM_ROOT *clone_mem_root_arg)
  :handler(hton, share)
{
  DBUG_ENTER("ha_partition::ha_partition(clone)");
  init_alloc_root(&m_mem_root, 512, 512);
  init_handler_variables();
  m_part_info= part_info_arg;
  m_create_handler= TRUE;
  m_is_sub_partitioned= m_part_info->is_sub_partitioned();
  m_is_clone_of= clone_arg;
  m_clone_mem_root= clone_mem_root_arg;
  DBUG_VOID_RETURN;
}

/*
  Initialize handler object

  SYNOPSIS
    init_handler_variables()

  RETURN VALUE
    NONE
*/

void ha_partition::init_handler_variables()
{
  active_index= MAX_KEY;
  m_mode= 0;
  m_open_test_lock= 0;
  m_file_buffer= NULL;
  m_name_buffer_ptr= NULL;
  m_engine_array= NULL;
  m_connect_string= NULL;
  m_file= NULL;
  m_file_tot_parts= 0;
  m_reorged_file= NULL;
  m_new_file= NULL;
  m_reorged_parts= 0;
  m_added_file= NULL;
  m_tot_parts= 0;
  m_pkey_is_clustered= 0;
  m_lock_type= F_UNLCK;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  m_scan_value= 2;
  m_ref_length= 0;
  m_part_spec.end_part= NO_CURRENT_PART_ID;
  m_index_scan_type= partition_no_index_scan;
  m_start_key.key= NULL;
  m_start_key.length= 0;
  m_myisam= FALSE;
  m_innodb= FALSE;
  m_extra_cache= FALSE;
  m_extra_cache_size= 0;
  m_extra_prepare_for_update= FALSE;
  m_extra_cache_part_id= NO_CURRENT_PART_ID;
  m_handler_status= handler_not_initialized;
  m_low_byte_first= 1;
  m_part_field_array= NULL;
  m_ordered_rec_buffer= NULL;
  m_top_entry= NO_CURRENT_PART_ID;
  m_rec_length= 0;
  m_last_part= 0;
  m_rec0= 0;
  m_curr_key_info[0]= NULL;
  m_curr_key_info[1]= NULL;
  m_part_func_monotonicity_info= NON_MONOTONIC;
  auto_increment_lock= FALSE;
  auto_increment_safe_stmt_log_lock= FALSE;
  /*
    this allows blackhole to work properly
  */
  m_no_locks= 0;
  m_part_info= NULL;
  m_create_handler= FALSE;
  m_is_sub_partitioned= 0;
  m_is_clone_of= NULL;
  m_clone_mem_root= NULL;

#ifdef DONT_HAVE_TO_BE_INITALIZED
  m_start_key.flag= 0;
  m_ordered= TRUE;
#endif
}


const char *ha_partition::table_type() const
{ 
  // we can do this since we only support a single engine type
  return m_file[0]->table_type(); 
}


/*
  Destructor method

  SYNOPSIS
    ~ha_partition()

  RETURN VALUE
    NONE
*/

ha_partition::~ha_partition()
{
  DBUG_ENTER("ha_partition::~ha_partition()");
  if (m_file != NULL)
  {
    uint i;
    for (i= 0; i < m_tot_parts; i++)
      delete m_file[i];
  }

  my_free(m_ordered_rec_buffer, MYF(MY_ALLOW_ZERO_PTR));
  m_ordered_rec_buffer= NULL;

  clear_handler_file();

  free_root(&m_mem_root, MYF(0));

  DBUG_VOID_RETURN;
}


/*
  Initialize partition handler object

  SYNOPSIS
    initialize_partition()
    mem_root			Allocate memory through this

  RETURN VALUE
    1                         Error
    0                         Success

  DESCRIPTION

  The partition handler is only a layer on top of other engines. Thus it
  can't really perform anything without the underlying handlers. Thus we
  add this method as part of the allocation of a handler object.

  1) Allocation of underlying handlers
     If we have access to the partition info we will allocate one handler
     instance for each partition.
  2) Allocation without partition info
     The cases where we don't have access to this information is when called
     in preparation for delete_table and rename_table and in that case we
     only need to set HA_FILE_BASED. In that case we will use the .par file
     that contains information about the partitions and their engines and
     the names of each partition.
  3) Table flags initialisation
     We need also to set table flags for the partition handler. This is not
     static since it depends on what storage engines are used as underlying
     handlers.
     The table flags is set in this routine to simulate the behaviour of a
     normal storage engine
     The flag HA_FILE_BASED will be set independent of the underlying handlers
  4) Index flags initialisation
     When knowledge exists on the indexes it is also possible to initialize the
     index flags. Again the index flags must be initialized by using the under-
     lying handlers since this is storage engine dependent.
     The flag HA_READ_ORDER will be reset for the time being to indicate no
     ordered output is available from partition handler indexes. Later a merge
     sort will be performed using the underlying handlers.
  5) primary_key_is_clustered, has_transactions and low_byte_first is
     calculated here.

*/

bool ha_partition::initialize_partition(MEM_ROOT *mem_root)
{
  handler **file_array, *file;
  ulonglong check_table_flags;
  DBUG_ENTER("ha_partition::initialize_partition");

  if (m_create_handler)
  {
    m_tot_parts= m_part_info->get_tot_partitions();
    DBUG_ASSERT(m_tot_parts > 0);
    if (new_handlers_from_part_info(mem_root))
      DBUG_RETURN(1);
  }
  else if (!table_share || !table_share->normalized_path.str)
  {
    /*
      Called with dummy table share (delete, rename and alter table).
      Don't need to set-up anything.
    */
    DBUG_RETURN(0);
  }
  else if (get_from_handler_file(table_share->normalized_path.str,
                                 mem_root, false))
  {
    my_message(ER_UNKNOWN_ERROR, "Failed to read from the .par file", MYF(0));
    DBUG_RETURN(1);
  }
  /*
    We create all underlying table handlers here. We do it in this special
    method to be able to report allocation errors.

    Set up low_byte_first, primary_key_is_clustered and
    has_transactions since they are called often in all kinds of places,
    other parameters are calculated on demand.
    Verify that all partitions have the same table_flags.
  */
  check_table_flags= m_file[0]->ha_table_flags();
  m_low_byte_first= m_file[0]->low_byte_first();
  m_pkey_is_clustered= TRUE;
  file_array= m_file;
  do
  {
    file= *file_array;
    if (m_low_byte_first != file->low_byte_first())
    {
      // Cannot have handlers with different endian
      my_error(ER_MIX_HANDLER_ERROR, MYF(0));
      DBUG_RETURN(1);
    }
    if (!file->primary_key_is_clustered())
      m_pkey_is_clustered= FALSE;
    if (check_table_flags != file->ha_table_flags())
    {
      my_error(ER_MIX_HANDLER_ERROR, MYF(0));
      DBUG_RETURN(1);
    }
  } while (*(++file_array));
  m_handler_status= handler_initialized;
  DBUG_RETURN(0);
}

/****************************************************************************
                MODULE meta data changes
****************************************************************************/
/*
  Delete a table

  SYNOPSIS
    delete_table()
    name                    Full path of table name

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    Used to delete a table. By the time delete_table() has been called all
    opened references to this table will have been closed (and your globally
    shared references released. The variable name will just be the name of
    the table. You will need to remove any files you have created at this
    point.

    If you do not implement this, the default delete_table() is called from
    handler.cc and it will delete all files with the file extentions returned
    by bas_ext().

    Called from handler.cc by delete_table and  ha_create_table(). Only used
    during create if the table_flag HA_DROP_BEFORE_CREATE was specified for
    the storage engine.
*/

int ha_partition::delete_table(const char *name)
{
  DBUG_ENTER("ha_partition::delete_table");

  DBUG_RETURN(del_ren_cre_table(name, NULL, NULL, NULL));
}


/*
  Rename a table

  SYNOPSIS
    rename_table()
    from                      Full path of old table name
    to                        Full path of new table name

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    Renames a table from one name to another from alter table call.

    If you do not implement this, the default rename_table() is called from
    handler.cc and it will rename all files with the file extentions returned
    by bas_ext().

    Called from sql_table.cc by mysql_rename_table().
*/

int ha_partition::rename_table(const char *from, const char *to)
{
  DBUG_ENTER("ha_partition::rename_table");

  DBUG_RETURN(del_ren_cre_table(from, to, NULL, NULL));
}


/*
  Create the handler file (.par-file)

  SYNOPSIS
    create_handler_files()
    name                              Full path of table name
    create_info                       Create info generated for CREATE TABLE

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    create_handler_files is called to create any handler specific files
    before opening the file with openfrm to later call ::create on the
    file object.
    In the partition handler this is used to store the names of partitions
    and types of engines in the partitions.
*/

int ha_partition::create_handler_files(const char *path,
                                       const char *old_path,
                                       int action_flag,
                                       HA_CREATE_INFO *create_info)
{
  DBUG_ENTER("ha_partition::create_handler_files()");

  /*
    We need to update total number of parts since we might write the handler
    file as part of a partition management command
  */
  if (action_flag == CHF_DELETE_FLAG ||
      action_flag == CHF_RENAME_FLAG)
  {
    char name[FN_REFLEN];
    char old_name[FN_REFLEN];

    strxmov(name, path, ha_par_ext, NullS);
    strxmov(old_name, old_path, ha_par_ext, NullS);
    if ((action_flag == CHF_DELETE_FLAG &&
         my_delete(name, MYF(MY_WME))) ||
        (action_flag == CHF_RENAME_FLAG &&
         my_rename(old_name, name, MYF(MY_WME))))
    {
      DBUG_RETURN(TRUE);
    }
  }
  else if (action_flag == CHF_CREATE_FLAG)
  {
    if (create_handler_file(path))
    {
      my_error(ER_CANT_CREATE_HANDLER_FILE, MYF(0));
      DBUG_RETURN(1);
    }
  }
  DBUG_RETURN(0);
}


/*
  Create a partitioned table

  SYNOPSIS
    create()
    name                              Full path of table name
    table_arg                         Table object
    create_info                       Create info generated for CREATE TABLE

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    create() is called to create a table. The variable name will have the name
    of the table. When create() is called you do not need to worry about
    opening the table. Also, the FRM file will have already been created so
    adjusting create_info will not do you any good. You can overwrite the frm
    file at this point if you wish to change the table definition, but there
    are no methods currently provided for doing that.

    Called from handler.cc by ha_create_table().
*/

int ha_partition::create(const char *name, TABLE *table_arg,
			 HA_CREATE_INFO *create_info)
{
  char t_name[FN_REFLEN];
  DBUG_ENTER("ha_partition::create");

  if (create_info->used_fields & HA_CREATE_USED_CONNECTION)
  {
    my_error(ER_CONNECT_TO_FOREIGN_DATA_SOURCE, MYF(0),
             "CONNECTION not valid for partition");
    DBUG_RETURN(1);
  }

  strmov(t_name, name);
  DBUG_ASSERT(*fn_rext((char*)name) == '\0');
  if (del_ren_cre_table(t_name, NULL, table_arg, create_info))
  {
    handler::delete_table(t_name);
    DBUG_RETURN(1);
  }
  DBUG_RETURN(0);
}


/*
  Drop partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    drop_partitions()
    path                        Complete path of db and table name

  RETURN VALUE
    >0                          Failure
    0                           Success

  DESCRIPTION
    Use part_info object on handler object to deduce which partitions to
    drop (each partition has a state attached to it)
*/

int ha_partition::drop_partitions(const char *path)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  char part_name_buff[FN_REFLEN];
  uint no_parts= m_part_info->partitions.elements;
  uint no_subparts= m_part_info->no_subparts;
  uint i= 0;
  uint name_variant;
  int  ret_error;
  int  error= 0;
  DBUG_ENTER("ha_partition::drop_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   part_name_buff)));
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_DROPPED)
    {
      handler *file;
      /*
        This part is to be dropped, meaning the part or all its subparts.
      */
      name_variant= NORMAL_PART_NAME;
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint j= 0, part;
        do
        {
          partition_element *sub_elem= sub_it++;
          part= i * no_subparts + j;
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name, name_variant);
          file= m_file[part];
          DBUG_PRINT("info", ("Drop subpartition %s", part_name_buff));
          if ((ret_error= file->ha_delete_table(part_name_buff)))
            error= ret_error;
          if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
        } while (++j < no_subparts);
      }
      else
      {
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, name_variant,
                              TRUE);
        file= m_file[i];
        DBUG_PRINT("info", ("Drop partition %s", part_name_buff));
        if ((ret_error= file->ha_delete_table(part_name_buff)))
          error= ret_error;
        if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
      }
      if (part_elem->part_state == PART_IS_CHANGED)
        part_elem->part_state= PART_NORMAL;
      else
        part_elem->part_state= PART_IS_DROPPED;
    }
  } while (++i < no_parts);
  VOID(sync_ddl_log());
  DBUG_RETURN(error);
}


/*
  Rename partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    rename_partitions()
    path                        Complete path of db and table name

  RETURN VALUE
    TRUE                        Failure
    FALSE                       Success

  DESCRIPTION
    When reorganising partitions, adding hash partitions and coalescing
    partitions it can be necessary to rename partitions while holding
    an exclusive lock on the table.
    Which partitions to rename is given by state of partitions found by the
    partition info struct referenced from the handler object
*/

int ha_partition::rename_partitions(const char *path)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  List_iterator<partition_element> temp_it(m_part_info->temp_partitions);
  char part_name_buff[FN_REFLEN];
  char norm_name_buff[FN_REFLEN];
  uint no_parts= m_part_info->partitions.elements;
  uint part_count= 0;
  uint no_subparts= m_part_info->no_subparts;
  uint i= 0;
  uint j= 0;
  int error= 0;
  int ret_error;
  uint temp_partitions= m_part_info->temp_partitions.elements;
  handler *file;
  partition_element *part_elem, *sub_elem;
  DBUG_ENTER("ha_partition::rename_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   norm_name_buff)));

  DEBUG_SYNC(ha_thd(), "before_rename_partitions");
  if (temp_partitions)
  {
    /*
      These are the reorganised partitions that have already been copied.
      We delete the partitions and log the delete by inactivating the
      delete log entry in the table log. We only need to synchronise
      these writes before moving to the next loop since there is no
      interaction among reorganised partitions, they cannot have the
      same name.
    */
    do
    {
      part_elem= temp_it++;
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        j= 0;
        do
        {
          sub_elem= sub_it++;
          file= m_reorged_file[part_count++];
          create_subpartition_name(norm_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   NORMAL_PART_NAME);
          DBUG_PRINT("info", ("Delete subpartition %s", norm_name_buff));
          if ((ret_error= file->ha_delete_table(norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
          else
            sub_elem->log_entry= NULL; /* Indicate success */
        } while (++j < no_subparts);
      }
      else
      {
        file= m_reorged_file[part_count++];
        create_partition_name(norm_name_buff, path,
                              part_elem->partition_name, NORMAL_PART_NAME,
                              TRUE);
        DBUG_PRINT("info", ("Delete partition %s", norm_name_buff));
        if ((ret_error= file->ha_delete_table(norm_name_buff)))
          error= ret_error;
        else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
        else
          part_elem->log_entry= NULL; /* Indicate success */
      }
    } while (++i < temp_partitions);
    VOID(sync_ddl_log());
  }
  i= 0;
  do
  {
    /*
       When state is PART_IS_CHANGED it means that we have created a new
       TEMP partition that is to be renamed to normal partition name and
       we are to delete the old partition with currently the normal name.
       
       We perform this operation by
       1) Delete old partition with normal partition name
       2) Signal this in table log entry
       3) Synch table log to ensure we have consistency in crashes
       4) Rename temporary partition name to normal partition name
       5) Signal this to table log entry
       It is not necessary to synch the last state since a new rename
       should not corrupt things if there was no temporary partition.

       The only other parts we need to cater for are new parts that
       replace reorganised parts. The reorganised parts were deleted
       by the code above that goes through the temp_partitions list.
       Thus the synch above makes it safe to simply perform step 4 and 5
       for those entries.
    */
    part_elem= part_it++;
    if (part_elem->part_state == PART_IS_CHANGED ||
        part_elem->part_state == PART_TO_BE_DROPPED ||
        (part_elem->part_state == PART_IS_ADDED && temp_partitions))
    {
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint part;

        j= 0;
        do
        {
          sub_elem= sub_it++;
          part= i * no_subparts + j;
          create_subpartition_name(norm_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   NORMAL_PART_NAME);
          if (part_elem->part_state == PART_IS_CHANGED)
          {
            file= m_reorged_file[part_count++];
            DBUG_PRINT("info", ("Delete subpartition %s", norm_name_buff));
            if ((ret_error= file->ha_delete_table(norm_name_buff)))
              error= ret_error;
            else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
              error= 1;
            VOID(sync_ddl_log());
          }
          file= m_new_file[part];
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   TEMP_PART_NAME);
          DBUG_PRINT("info", ("Rename subpartition from %s to %s",
                     part_name_buff, norm_name_buff));
          if ((ret_error= file->ha_rename_table(part_name_buff,
                                                norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
          else
            sub_elem->log_entry= NULL;
        } while (++j < no_subparts);
      }
      else
      {
        create_partition_name(norm_name_buff, path,
                              part_elem->partition_name, NORMAL_PART_NAME,
                              TRUE);
        if (part_elem->part_state == PART_IS_CHANGED)
        {
          file= m_reorged_file[part_count++];
          DBUG_PRINT("info", ("Delete partition %s", norm_name_buff));
          if ((ret_error= file->ha_delete_table(norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
            error= 1;
          VOID(sync_ddl_log());
        }
        file= m_new_file[i];
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, TEMP_PART_NAME,
                              TRUE);
        DBUG_PRINT("info", ("Rename partition from %s to %s",
                   part_name_buff, norm_name_buff));
        if ((ret_error= file->ha_rename_table(part_name_buff,
                                              norm_name_buff)))
          error= ret_error;
        else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
        else
          part_elem->log_entry= NULL;
      }
    }
  } while (++i < no_parts);
  VOID(sync_ddl_log());
  DBUG_RETURN(error);
}


#define OPTIMIZE_PARTS 1
#define ANALYZE_PARTS 2
#define CHECK_PARTS   3
#define REPAIR_PARTS 4

static const char *opt_op_name[]= {NULL,
                                   "optimize", "analyze", "check", "repair" };

/*
  Optimize table

  SYNOPSIS
    optimize()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::optimize(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::optimize");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, OPTIMIZE_PARTS));
}


/*
  Analyze table

  SYNOPSIS
    analyze()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::analyze(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::analyze");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, ANALYZE_PARTS));
}


/*
  Check table

  SYNOPSIS
    check()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::check(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::check");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, CHECK_PARTS));
}


/*
  Repair table

  SYNOPSIS
    repair()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::repair(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::repair");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, REPAIR_PARTS));
}


/*
  Handle optimize/analyze/check/repair of one partition

  SYNOPSIS
    handle_opt_part()
    thd                      Thread object
    check_opt                Options
    file                     Handler object of partition
    flag                     Optimize/Analyze/Check/Repair flag

  RETURN VALUE
    >0                        Failure
    0                         Success
*/

static int handle_opt_part(THD *thd, HA_CHECK_OPT *check_opt,
                           handler *file, uint flag)
{
  int error;
  DBUG_ENTER("handle_opt_part");
  DBUG_PRINT("enter", ("flag = %u", flag));

  if (flag == OPTIMIZE_PARTS)
    error= file->ha_optimize(thd, check_opt);
  else if (flag == ANALYZE_PARTS)
    error= file->ha_analyze(thd, check_opt);
  else if (flag == CHECK_PARTS)
    error= file->ha_check(thd, check_opt);
  else if (flag == REPAIR_PARTS)
    error= file->ha_repair(thd, check_opt);
  else
  {
    DBUG_ASSERT(FALSE);
    error= 1;
  }
  if (error == HA_ADMIN_ALREADY_DONE)
    error= 0;
  DBUG_RETURN(error);
}


/*
   print a message row formatted for ANALYZE/CHECK/OPTIMIZE/REPAIR TABLE 
   (modelled after mi_check_print_msg)
   TODO: move this into the handler, or rewrite mysql_admin_table.
*/
static bool print_admin_msg(THD* thd, const char* msg_type,
                            const char* db_name, const char* table_name,
                            const char* op_name, const char *fmt, ...)
  ATTRIBUTE_FORMAT(printf, 6, 7);
static bool print_admin_msg(THD* thd, const char* msg_type,
                            const char* db_name, const char* table_name,
                            const char* op_name, const char *fmt, ...)
{
  va_list args;
  Protocol *protocol= thd->protocol;
  uint length, msg_length;
  char msgbuf[HA_MAX_MSG_BUF];
  char name[SAFE_NAME_LEN*2+2];

  va_start(args, fmt);
  msg_length= my_vsnprintf(msgbuf, sizeof(msgbuf), fmt, args);
  va_end(args);
  msgbuf[sizeof(msgbuf) - 1] = 0; // healthy paranoia


  if (!thd->vio_ok())
  {
    sql_print_error(fmt, args);
    return TRUE;
  }

  length=(uint) (strxmov(name, db_name, ".", table_name,NullS) - name);
  /*
     TODO: switch from protocol to push_warning here. The main reason we didn't
     it yet is parallel repair. Due to following trace:
     mi_check_print_msg/push_warning/sql_alloc/my_pthread_getspecific_ptr.

     Also we likely need to lock mutex here (in both cases with protocol and
     push_warning).
  */
  DBUG_PRINT("info",("print_admin_msg:  %s, %s, %s, %s", name, op_name,
                     msg_type, msgbuf));
  protocol->prepare_for_resend();
  protocol->store(name, length, system_charset_info);
  protocol->store(op_name, system_charset_info);
  protocol->store(msg_type, system_charset_info);
  protocol->store(msgbuf, msg_length, system_charset_info);
  if (protocol->write())
  {
    sql_print_error("Failed on my_net_write, writing to stderr instead: %s\n",
                    msgbuf);
    return TRUE;
  }
  return FALSE;
}


/*
  Handle optimize/analyze/check/repair of partitions

  SYNOPSIS
    handle_opt_partitions()
    thd                      Thread object
    check_opt                Options
    flag                     Optimize/Analyze/Check/Repair flag

  RETURN VALUE
    >0                        Failure
    0                         Success
*/

int ha_partition::handle_opt_partitions(THD *thd, HA_CHECK_OPT *check_opt,
                                        uint flag)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  uint no_parts= m_part_info->no_parts;
  uint no_subparts= m_part_info->no_subparts;
  uint i= 0;
  int error;
  DBUG_ENTER("ha_partition::handle_opt_partitions");
  DBUG_PRINT("enter", ("flag= %u", flag));

  do
  {
    partition_element *part_elem= part_it++;
    /*
      when ALTER TABLE <CMD> PARTITION ...
      it should only do named partitions, otherwise all partitions
    */
    if (!(thd->lex->alter_info.flags & ALTER_ADMIN_PARTITION) ||
        part_elem->part_state == PART_CHANGED)
    {
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> subpart_it(part_elem->subpartitions);
        partition_element *sub_elem;
        uint j= 0, part;
        do
        {
          sub_elem= subpart_it++;
          part= i * no_subparts + j;
          DBUG_PRINT("info", ("Optimize subpartition %u (%s)",
                     part, sub_elem->partition_name));
#ifdef NOT_USED
          if (print_admin_msg(thd, "note", table_share->db.str, table->alias,
                          opt_op_name[flag],
                          "Start to operate on subpartition %s", 
                          sub_elem->partition_name))
            DBUG_RETURN(HA_ADMIN_INTERNAL_ERROR);
#endif
          if ((error= handle_opt_part(thd, check_opt, m_file[part], flag)))
          {
            /* print a line which partition the error belongs to */
            if (error != HA_ADMIN_NOT_IMPLEMENTED &&
                error != HA_ADMIN_ALREADY_DONE &&
                error != HA_ADMIN_TRY_ALTER)
            {
              print_admin_msg(thd, "error", table_share->db.str, table->alias,
                              opt_op_name[flag],
                              "Subpartition %s returned error", 
                              sub_elem->partition_name);
            }
            DBUG_RETURN(error);
          }
        } while (++j < no_subparts);
      }
      else
      {
        DBUG_PRINT("info", ("Optimize partition %u (%s)", i,
                            part_elem->partition_name));
#ifdef NOT_USED
        if (print_admin_msg(thd, "note", table_share->db.str, table->alias,
                        opt_op_name[flag],
                        "Start to operate on partition %s", 
                        part_elem->partition_name))
          DBUG_RETURN(HA_ADMIN_INTERNAL_ERROR);
#endif
        if ((error= handle_opt_part(thd, check_opt, m_file[i], flag)))
        {
          /* print a line which partition the error belongs to */
          if (error != HA_ADMIN_NOT_IMPLEMENTED &&
              error != HA_ADMIN_ALREADY_DONE &&
              error != HA_ADMIN_TRY_ALTER)
          {
            print_admin_msg(thd, "error", table_share->db.str, table->alias,
                            opt_op_name[flag], "Partition %s returned error", 
                            part_elem->partition_name);
          }
          DBUG_RETURN(error);
        }
      }
    }
  } while (++i < no_parts);
  DBUG_RETURN(FALSE);
}


/**
  @brief Check and repair the table if neccesary

  @param thd    Thread object

  @retval TRUE  Error/Not supported
  @retval FALSE Success
*/

bool ha_partition::check_and_repair(THD *thd)
{
  handler **file= m_file;
  DBUG_ENTER("ha_partition::check_and_repair");

  do
  {
    if ((*file)->ha_check_and_repair(thd))
      DBUG_RETURN(TRUE);
  } while (*(++file));
  DBUG_RETURN(FALSE);
}
 

/**
  @breif Check if the table can be automatically repaired

  @retval TRUE  Can be auto repaired
  @retval FALSE Cannot be auto repaired
*/

bool ha_partition::auto_repair(int error) const
{
  DBUG_ENTER("ha_partition::auto_repair");

  /*
    As long as we only support one storage engine per table,
    we can use the first partition for this function.
  */
  DBUG_RETURN(m_file[0]->auto_repair(error));
}


/**
  @breif Check if the table is crashed

  @retval TRUE  Crashed
  @retval FALSE Not crashed
*/

bool ha_partition::is_crashed() const
{
  handler **file= m_file;
  DBUG_ENTER("ha_partition::is_crashed");

  do
  {
    if ((*file)->is_crashed())
      DBUG_RETURN(TRUE);
  } while (*(++file));
  DBUG_RETURN(FALSE);
}
 

/*
  Prepare by creating a new partition

  SYNOPSIS
    prepare_new_partition()
    table                      Table object
    create_info                Create info from CREATE TABLE
    file                       Handler object of new partition
    part_name                  partition name

  RETURN VALUE
    >0                         Error
    0                          Success
*/

int ha_partition::prepare_new_partition(TABLE *tbl,
                                        HA_CREATE_INFO *create_info,
                                        handler *file, const char *part_name,
                                        partition_element *p_elem)
{
  int error;
  DBUG_ENTER("prepare_new_partition");

  if ((error= set_up_table_before_create(tbl, part_name, create_info,
                                         0, p_elem)))
    goto error_create;
  tbl->s->connect_string = p_elem->connect_string;
  if ((error= file->ha_create(part_name, tbl, create_info)))
  {
    /*
      Added for safety, InnoDB reports HA_ERR_FOUND_DUPP_KEY
      if the table/partition already exists.
      If we return that error code, then print_error would try to
      get_dup_key on a non-existing partition.
      So return a more reasonable error code.
    */
    if (error == HA_ERR_FOUND_DUPP_KEY)
      error= HA_ERR_TABLE_EXIST;
    goto error_create;
  }
  DBUG_PRINT("info", ("partition %s created", part_name));
  if ((error= file->ha_open(tbl, part_name, m_mode, m_open_test_lock)))
    goto error_open;
  DBUG_PRINT("info", ("partition %s opened", part_name));
  /*
    Note: if you plan to add another call that may return failure,
    better to do it before external_lock() as cleanup_new_partition()
    assumes that external_lock() is last call that may fail here.
    Otherwise see description for cleanup_new_partition().
  */
  if ((error= file->ha_external_lock(ha_thd(), m_lock_type)))
    goto error_external_lock;
  DBUG_PRINT("info", ("partition %s external locked", part_name));

  DBUG_RETURN(0);
error_external_lock:
  VOID(file->close());
error_open:
  VOID(file->ha_delete_table(part_name));
error_create:
  DBUG_RETURN(error);
}


/*
  Cleanup by removing all created partitions after error

  SYNOPSIS
    cleanup_new_partition()
    part_count             Number of partitions to remove

  RETURN VALUE
    NONE

  DESCRIPTION
    This function is called immediately after prepare_new_partition() in
    case the latter fails.

    In prepare_new_partition() last call that may return failure is
    external_lock(). That means if prepare_new_partition() fails,
    partition does not have external lock. Thus no need to call
    external_lock(F_UNLCK) here.

  TODO:
    We must ensure that in the case that we get an error during the process
    that we call external_lock with F_UNLCK, close the table and delete the
    table in the case where we have been successful with prepare_handler.
    We solve this by keeping an array of successful calls to prepare_handler
    which can then be used to undo the call.
*/

void ha_partition::cleanup_new_partition(uint part_count)
{
  DBUG_ENTER("ha_partition::cleanup_new_partition");

  if (m_added_file)
  {
    THD *thd= ha_thd();
    handler **file= m_added_file;
    while ((part_count > 0) && (*file))
    {
      (*file)->ha_external_lock(thd, F_UNLCK);
      (*file)->close();

      /* Leave the (*file)->ha_delete_table(part_name) to the ddl-log */

      file++;
      part_count--;
    }
    m_added_file= NULL;
  }
  DBUG_VOID_RETURN;
}

/*
  Implement the partition changes defined by ALTER TABLE of partitions

  SYNOPSIS
    change_partitions()
    create_info                 HA_CREATE_INFO object describing all
                                fields and indexes in table
    path                        Complete path of db and table name
    out: copied                 Output parameter where number of copied
                                records are added
    out: deleted                Output parameter where number of deleted
                                records are added
    pack_frm_data               Reference to packed frm file
    pack_frm_len                Length of packed frm file

  RETURN VALUE
    >0                        Failure
    0                         Success

  DESCRIPTION
    Add and copy if needed a number of partitions, during this operation
    no other operation is ongoing in the server. This is used by
    ADD PARTITION all types as well as by REORGANIZE PARTITION. For
    one-phased implementations it is used also by DROP and COALESCE
    PARTITIONs.
    One-phased implementation needs the new frm file, other handlers will
    get zero length and a NULL reference here.
*/

int ha_partition::change_partitions(HA_CREATE_INFO *create_info,
                                    const char *path,
                                    ulonglong * const copied,
                                    ulonglong * const deleted,
                                    const uchar *pack_frm_data
                                    __attribute__((unused)),
                                    size_t pack_frm_len
                                    __attribute__((unused)))
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  List_iterator <partition_element> t_it(m_part_info->temp_partitions);
  char part_name_buff[FN_REFLEN];
  uint no_parts= m_part_info->partitions.elements;
  uint no_subparts= m_part_info->no_subparts;
  uint i= 0;
  uint no_remain_partitions, part_count, orig_count;
  handler **new_file_array;
  int error= 1;
  bool first;
  uint temp_partitions= m_part_info->temp_partitions.elements;
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::change_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   part_name_buff)));
  m_reorged_parts= 0;
  if (!m_part_info->is_sub_partitioned())
    no_subparts= 1;

  /*
    Step 1:
      Calculate number of reorganised partitions and allocate space for
      their handler references.
  */
  if (temp_partitions)
  {
    m_reorged_parts= temp_partitions * no_subparts;
  }
  else
  {
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_CHANGED ||
          part_elem->part_state == PART_REORGED_DROPPED)
      {
        m_reorged_parts+= no_subparts;
      }
    } while (++i < no_parts);
  }
  if (m_reorged_parts &&
      !(m_reorged_file= (handler**)sql_calloc(sizeof(handler*)*
                                              (m_reorged_parts + 1))))
  {
    mem_alloc_error(sizeof(handler*)*(m_reorged_parts+1));
    DBUG_RETURN(ER_OUTOFMEMORY);
  }

  /*
    Step 2:
      Calculate number of partitions after change and allocate space for
      their handler references.
  */
  no_remain_partitions= 0;
  if (temp_partitions)
  {
    no_remain_partitions= no_parts * no_subparts;
  }
  else
  {
    part_it.rewind();
    i= 0;
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_NORMAL ||
          part_elem->part_state == PART_TO_BE_ADDED ||
          part_elem->part_state == PART_CHANGED)
      {
        no_remain_partitions+= no_subparts;
      }
    } while (++i < no_parts);
  }
  if (!(new_file_array= (handler**)sql_calloc(sizeof(handler*)*
                                              (2*(no_remain_partitions + 1)))))
  {
    mem_alloc_error(sizeof(handler*)*2*(no_remain_partitions+1));
    DBUG_RETURN(ER_OUTOFMEMORY);
  }
  m_added_file= &new_file_array[no_remain_partitions + 1];

  /*
    Step 3:
      Fill m_reorged_file with handler references and NULL at the end
  */
  if (m_reorged_parts)
  {
    i= 0;
    part_count= 0;
    first= TRUE;
    part_it.rewind();
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_CHANGED ||
          part_elem->part_state == PART_REORGED_DROPPED)
      {
        memcpy((void*)&m_reorged_file[part_count],
               (void*)&m_file[i*no_subparts],
               sizeof(handler*)*no_subparts);
        part_count+= no_subparts;
      }
      else if (first && temp_partitions &&
               part_elem->part_state == PART_TO_BE_ADDED)
      {
        /*
          When doing an ALTER TABLE REORGANIZE PARTITION a number of
          partitions is to be reorganised into a set of new partitions.
          The reorganised partitions are in this case in the temp_partitions
          list. We copy all of them in one batch and thus we only do this
          until we find the first partition with state PART_TO_BE_ADDED
          since this is where the new partitions go in and where the old
          ones used to be.
        */
        first= FALSE;
        DBUG_ASSERT(((i*no_subparts) + m_reorged_parts) <= m_file_tot_parts);
        memcpy((void*)m_reorged_file, &m_file[i*no_subparts],
               sizeof(handler*)*m_reorged_parts);
      }
    } while (++i < no_parts);
  }

  /*
    Step 4:
      Fill new_array_file with handler references. Create the handlers if
      needed.
  */
  i= 0;
  part_count= 0;
  orig_count= 0;
  first= TRUE;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_NORMAL)
    {
      DBUG_ASSERT(orig_count + no_subparts <= m_file_tot_parts);
      memcpy((void*)&new_file_array[part_count], (void*)&m_file[orig_count],
             sizeof(handler*)*no_subparts);
      part_count+= no_subparts;
      orig_count+= no_subparts;
    }
    else if (part_elem->part_state == PART_CHANGED ||
             part_elem->part_state == PART_TO_BE_ADDED)
    {
      uint j= 0;
      do
      {
        if (!(new_file_array[part_count++]=
              get_new_handler(table->s,
                              thd->mem_root,
                              part_elem->engine_type)))
        {
          mem_alloc_error(sizeof(handler));
          DBUG_RETURN(ER_OUTOFMEMORY);
        }
      } while (++j < no_subparts);
      if (part_elem->part_state == PART_CHANGED)
        orig_count+= no_subparts;
      else if (temp_partitions && first)
      {
        orig_count+= (no_subparts * temp_partitions);
        first= FALSE;
      }
    }
  } while (++i < no_parts);
  first= FALSE;
  /*
    Step 5:
      Create the new partitions and also open, lock and call external_lock
      on them to prepare them for copy phase and also for later close
      calls
  */
  i= 0;
  part_count= 0;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_ADDED ||
        part_elem->part_state == PART_CHANGED)
    {
      /*
        A new partition needs to be created PART_TO_BE_ADDED means an
        entirely new partition and PART_CHANGED means a changed partition
        that will still exist with either more or less data in it.
      */
      uint name_variant= NORMAL_PART_NAME;
      if (part_elem->part_state == PART_CHANGED ||
          (part_elem->part_state == PART_TO_BE_ADDED && temp_partitions))
        name_variant= TEMP_PART_NAME;
      if (m_part_info->is_sub_partitioned())
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint j= 0, part;
        do
        {
          partition_element *sub_elem= sub_it++;
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   name_variant);
          part= i * no_subparts + j;
          DBUG_PRINT("info", ("Add subpartition %s", part_name_buff));
          if ((error= prepare_new_partition(table, create_info,
                                            new_file_array[part],
                                            (const char *)part_name_buff,
                                            sub_elem)))
          {
            cleanup_new_partition(part_count);
            DBUG_RETURN(error);
          }
          m_added_file[part_count++]= new_file_array[part];
        } while (++j < no_subparts);
      }
      else
      {
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, name_variant,
                              TRUE);
        DBUG_PRINT("info", ("Add partition %s", part_name_buff));
        if ((error= prepare_new_partition(table, create_info,
                                          new_file_array[i],
                                          (const char *)part_name_buff,
                                          part_elem)))
        {
          cleanup_new_partition(part_count);
          DBUG_RETURN(error);
        }
        m_added_file[part_count++]= new_file_array[i];
      }
    }
  } while (++i < no_parts);

  /*
    Step 6:
      State update to prepare for next write of the frm file.
  */
  i= 0;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_ADDED)
      part_elem->part_state= PART_IS_ADDED;
    else if (part_elem->part_state == PART_CHANGED)
      part_elem->part_state= PART_IS_CHANGED;
    else if (part_elem->part_state == PART_REORGED_DROPPED)
      part_elem->part_state= PART_TO_BE_DROPPED;
  } while (++i < no_parts);
  for (i= 0; i < temp_partitions; i++)
  {
    partition_element *part_elem= t_it++;
    DBUG_ASSERT(part_elem->part_state == PART_TO_BE_REORGED);
    part_elem->part_state= PART_TO_BE_DROPPED;
  }
  m_new_file= new_file_array;
  if ((error= copy_partitions(copied, deleted)))
  {
    /*
      Close and unlock the new temporary partitions.
      They will later be deleted through the ddl-log.
    */
    cleanup_new_partition(part_count);
  }
  DBUG_RETURN(error);
}


/*
  Copy partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    copy_partitions()
    out:copied                 Number of records copied
    out:deleted                Number of records deleted

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    change_partitions has done all the preparations, now it is time to
    actually copy the data from the reorganised partitions to the new
    partitions.
*/

int ha_partition::copy_partitions(ulonglong * const copied,
                                  ulonglong * const deleted)
{
  uint reorg_part= 0;
  int result= 0;
  longlong func_value;
  DBUG_ENTER("ha_partition::copy_partitions");

  if (m_part_info->linear_hash_ind)
  {
    if (m_part_info->part_type == HASH_PARTITION)
      set_linear_hash_mask(m_part_info, m_part_info->no_parts);
    else
      set_linear_hash_mask(m_part_info, m_part_info->no_subparts);
  }

  while (reorg_part < m_reorged_parts)
  {
    handler *file= m_reorged_file[reorg_part];
    uint32 new_part;

    late_extra_cache(reorg_part);
    if ((result= file->ha_rnd_init(1)))
      goto error;
    while (TRUE)
    {
      if ((result= file->rnd_next(m_rec0)))
      {
        if (result == HA_ERR_RECORD_DELETED)
          continue;                              //Probably MyISAM
        if (result != HA_ERR_END_OF_FILE)
          goto error;
        /*
          End-of-file reached, break out to continue with next partition or
          end the copy process.
        */
        break;
      }
      /* Found record to insert into new handler */
      if (m_part_info->get_partition_id(m_part_info, &new_part,
                                        &func_value))
      {
        /*
           This record is in the original table but will not be in the new
           table since it doesn't fit into any partition any longer due to
           changed partitioning ranges or list values.
        */
        (*deleted)++;
      }
      else
      {
        THD *thd= ha_thd();
        /* Copy record to new handler */
        (*copied)++;
        tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
        result= m_new_file[new_part]->ha_write_row(m_rec0);
        reenable_binlog(thd);
        if (result)
          goto error;
      }
    }
    late_extra_no_cache(reorg_part);
    file->ha_rnd_end();
    reorg_part++;
  }
  DBUG_RETURN(FALSE);
error:
  m_reorged_file[reorg_part]->ha_rnd_end();
  DBUG_RETURN(result);
}


/*
  Update create info as part of ALTER TABLE

  SYNOPSIS
    update_create_info()
    create_info                   Create info from ALTER TABLE

  RETURN VALUE
    NONE

  DESCRIPTION
    Method empty so far
*/

void ha_partition::update_create_info(HA_CREATE_INFO *create_info)
{
  /*
    Fix for bug#38751, some engines needs info-calls in ALTER.
    Archive need this since it flushes in ::info.
    HA_STATUS_AUTO is optimized so it will not always be forwarded
    to all partitions, but HA_STATUS_VARIABLE will.
  */
  info(HA_STATUS_VARIABLE);

  info(HA_STATUS_AUTO);

  if (!(create_info->used_fields & HA_CREATE_USED_AUTO))
    create_info->auto_increment_value= stats.auto_increment_value;

  create_info->data_file_name= create_info->index_file_name = NULL;
  create_info->connect_string.str= NULL;
  create_info->connect_string.length= 0;
  return;
}


void ha_partition::change_table_ptr(TABLE *table_arg, TABLE_SHARE *share)
{
  handler **file_array;
  table= table_arg;
  table_share= share;
  /*
    m_file can be NULL when using an old cached table in DROP TABLE, when the
    table just has REMOVED PARTITIONING, see Bug#42438
  */
  if (m_file)
  {
    file_array= m_file;
    DBUG_ASSERT(*file_array);
    do
    {
      (*file_array)->change_table_ptr(table_arg, share);
    } while (*(++file_array));
  }

  if (m_added_file && m_added_file[0])
  {
    /* if in middle of a drop/rename etc */
    file_array= m_added_file;
    do
    {
      (*file_array)->change_table_ptr(table_arg, share);
    } while (*(++file_array));
  }
}

/*
  Change comments specific to handler

  SYNOPSIS
    update_table_comment()
    comment                       Original comment

  RETURN VALUE
    new comment 

  DESCRIPTION
    No comment changes so far
*/

char *ha_partition::update_table_comment(const char *comment)
{
  return (char*) comment;                       /* Nothing to change */
}



/*
  Handle delete, rename and create table

  SYNOPSIS
    del_ren_cre_table()
    from                    Full path of old table
    to                      Full path of new table
    table_arg               Table object
    create_info             Create info

  RETURN VALUE
    >0                      Error
    0                       Success

  DESCRIPTION
    Common routine to handle delete_table and rename_table.
    The routine uses the partition handler file to get the
    names of the partition instances. Both these routines
    are called after creating the handler without table
    object and thus the file is needed to discover the
    names of the partitions and the underlying storage engines.
*/

uint ha_partition::del_ren_cre_table(const char *from,
				     const char *to,
				     TABLE *table_arg,
				     HA_CREATE_INFO *create_info)
{
  int save_error= 0;
  int error;
  char from_buff[FN_REFLEN], to_buff[FN_REFLEN], from_lc_buff[FN_REFLEN],
       to_lc_buff[FN_REFLEN];
  char *name_buffer_ptr;
  const char *from_path;
  const char *to_path= NULL;
  uint i;
  handler **file, **abort_file;
  DBUG_ENTER("del_ren_cre_table()");

  /* Not allowed to create temporary partitioned tables */
  if (create_info && create_info->options & HA_LEX_CREATE_TMP_TABLE)
  {
    my_error(ER_PARTITION_NO_TEMPORARY, MYF(0));
    DBUG_RETURN(TRUE);
  }

  if (get_from_handler_file(from, ha_thd()->mem_root, false))
    DBUG_RETURN(TRUE);
  DBUG_ASSERT(m_file_buffer);
  DBUG_PRINT("enter", ("from: (%s) to: (%s)", from, to));
  name_buffer_ptr= m_name_buffer_ptr;
  file= m_file;
  if (to == NULL && table_arg == NULL)
  {
    /*
      Delete table, start by delete the .par file. If error, break, otherwise
      delete as much as possible.
    */
    if ((error= handler::delete_table(from)))
      DBUG_RETURN(error);
  }
  /*
    Since ha_partition has HA_FILE_BASED, it must alter underlying table names
    if they do not have HA_FILE_BASED and lower_case_table_names == 2.
    See Bug#37402, for Mac OS X.
    The appended #P#<partname>[#SP#<subpartname>] will remain in current case.
    Using the first partitions handler, since mixing handlers is not allowed.
  */
  from_path= get_canonical_filename(*file, from, from_lc_buff);
  if (to != NULL)
    to_path= get_canonical_filename(*file, to, to_lc_buff);
  i= 0;
  do
  {
    create_partition_name(from_buff, from_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);

    if (to != NULL)
    {						// Rename branch
      create_partition_name(to_buff, to_path, name_buffer_ptr,
                            NORMAL_PART_NAME, FALSE);
      error= (*file)->ha_rename_table(from_buff, to_buff);
      if (error)
        goto rename_error;
    }
    else if (table_arg == NULL)			// delete branch
      error= (*file)->ha_delete_table(from_buff);
    else
    {
      if ((error= set_up_table_before_create(table_arg, from_buff,
                                             create_info, i, NULL)) ||
          ((error= (*file)->ha_create(from_buff, table_arg, create_info))))
        goto create_error;
    }
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
    if (error)
      save_error= error;
    i++;
  } while (*(++file));
  if (to != NULL)
  {
    if ((error= handler::rename_table(from, to)))
    {
      /* Try to revert everything, ignore errors */
      (void) handler::rename_table(to, from);
      goto rename_error;
    }
  }
  DBUG_RETURN(save_error);
create_error:
  name_buffer_ptr= m_name_buffer_ptr;
  for (abort_file= file, file= m_file; file < abort_file; file++)
  {
    create_partition_name(from_buff, from_path, name_buffer_ptr, NORMAL_PART_NAME,
                          FALSE);
    (void) (*file)->ha_delete_table((const char*) from_buff);
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
  }
  DBUG_RETURN(error);
rename_error:
  name_buffer_ptr= m_name_buffer_ptr;
  for (abort_file= file, file= m_file; file < abort_file; file++)
  {
    /* Revert the rename, back from 'to' to the original 'from' */
    create_partition_name(from_buff, from_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);
    create_partition_name(to_buff, to_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);
    /* Ignore error here */
    (void) (*file)->ha_rename_table(to_buff, from_buff);
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
  }
  DBUG_RETURN(error);
}

/*
  Find partition based on partition id

  SYNOPSIS
    find_partition_element()
    part_id                   Partition id of partition looked for

  RETURN VALUE
    >0                        Reference to partition_element
    0                         Partition not found
*/

partition_element *ha_partition::find_partition_element(uint part_id)
{
  uint i;
  uint curr_part_id= 0;
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);

  for (i= 0; i < m_part_info->no_parts; i++)
  {
    partition_element *part_elem;
    part_elem= part_it++;
    if (m_is_sub_partitioned)
    {
      uint j;
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->no_subparts; j++)
      {
	part_elem= sub_it++;
	if (part_id == curr_part_id++)
	  return part_elem;
      }
    }
    else if (part_id == curr_part_id++)
      return part_elem;
  }
  DBUG_ASSERT(0);
  my_error(ER_OUT_OF_RESOURCES, MYF(0));
  current_thd->fatal_error();                   // Abort
  return NULL;
}


/*
   Set up table share object before calling create on underlying handler

   SYNOPSIS
     set_up_table_before_create()
     table                       Table object
     info                        Create info
     part_id                     Partition id of partition to set-up

   RETURN VALUE
     TRUE                        Error
     FALSE                       Success

   DESCRIPTION
     Set up
     1) Comment on partition
     2) MAX_ROWS, MIN_ROWS on partition
     3) Index file name on partition
     4) Data file name on partition
*/

int ha_partition::set_up_table_before_create(TABLE *tbl,
                    const char *partition_name_with_path, 
                    HA_CREATE_INFO *info,
                    uint part_id,
                    partition_element *part_elem)
{
  int error= 0;
  const char *partition_name;
  THD *thd= ha_thd();
  DBUG_ENTER("set_up_table_before_create");

  if (!part_elem)
  {
    part_elem= find_partition_element(part_id);
    if (!part_elem)
      DBUG_RETURN(1);                             // Fatal error
  }
  tbl->s->max_rows= part_elem->part_max_rows;
  tbl->s->min_rows= part_elem->part_min_rows;
  partition_name= strrchr(partition_name_with_path, FN_LIBCHAR);
  if ((part_elem->index_file_name &&
      (error= append_file_to_dir(thd,
                                 (const char**)&part_elem->index_file_name,
                                 partition_name+1))) ||
      (part_elem->data_file_name &&
      (error= append_file_to_dir(thd,
                                 (const char**)&part_elem->data_file_name,
                                 partition_name+1))))
  {
    DBUG_RETURN(error);
  }
  info->index_file_name= part_elem->index_file_name;
  info->data_file_name= part_elem->data_file_name;
  info->connect_string= part_elem->connect_string;
  if (info->connect_string.length)
    info->used_fields|= HA_CREATE_USED_CONNECTION;
  tbl->s->connect_string= part_elem->connect_string;
  DBUG_RETURN(0);
}


/*
  Add two names together

  SYNOPSIS
    name_add()
    out:dest                          Destination string
    first_name                        First name
    sec_name                          Second name

  RETURN VALUE
    >0                                Error
    0                                 Success

  DESCRIPTION
    Routine used to add two names with '_' in between then. Service routine
    to create_handler_file
    Include the NULL in the count of characters since it is needed as separator
    between the partition names.
*/

static uint name_add(char *dest, const char *first_name, const char *sec_name)
{
  return (uint) (strxmov(dest, first_name, "#SP#", sec_name, NullS) -dest) + 1;
}


/**
  Create the special .par file

  @param name  Full path of table name

  @return Operation status
    @retval FALSE  Error code
    @retval TRUE   Success

  @note
    Method used to create handler file with names of partitions, their
    engine types and the number of partitions.
*/

bool ha_partition::create_handler_file(const char *name)
{
  partition_element *part_elem, *subpart_elem;
  uint i, j, part_name_len, subpart_name_len;
  uint tot_partition_words, tot_name_len, no_parts;
  uint tot_parts= 0;
  uint tot_len_words, tot_len_byte, chksum, tot_name_words;
  char *name_buffer_ptr;
  uchar *file_buffer, *engine_array;
  bool result= TRUE;
  char file_name[FN_REFLEN];
  char part_name[FN_REFLEN];
  char subpart_name[FN_REFLEN];
  File file;
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);
  DBUG_ENTER("create_handler_file");

  no_parts= m_part_info->partitions.elements;
  DBUG_PRINT("info", ("table name = %s, no_parts = %u", name,
                      no_parts));
  tot_name_len= 0;
  for (i= 0; i < no_parts; i++)
  {
    part_elem= part_it++;
    if (part_elem->part_state != PART_NORMAL &&
        part_elem->part_state != PART_TO_BE_ADDED &&
        part_elem->part_state != PART_CHANGED)
      continue;
    tablename_to_filename(part_elem->partition_name, part_name,
                          FN_REFLEN);
    part_name_len= strlen(part_name);
    if (!m_is_sub_partitioned)
    {
      tot_name_len+= part_name_len + 1;
      tot_parts++;
    }
    else
    {
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->no_subparts; j++)
      {
	subpart_elem= sub_it++;
        tablename_to_filename(subpart_elem->partition_name,
                              subpart_name,
                              FN_REFLEN);
	subpart_name_len= strlen(subpart_name);
	tot_name_len+= part_name_len + subpart_name_len + 5;
        tot_parts++;
      }
    }
  }
  /*
     File format:
     Length in words              4 byte
     Checksum                     4 byte
     Total number of partitions   4 byte
     Array of engine types        n * 4 bytes where
     n = (m_tot_parts + 3)/4
     Length of name part in bytes 4 bytes
     (Names in filename format)
     Name part                    m * 4 bytes where
     m = ((length_name_part + 3)/4)*4

     All padding bytes are zeroed
  */
  tot_partition_words= (tot_parts + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;
  tot_name_words= (tot_name_len + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;
  /* 4 static words (tot words, checksum, tot partitions, name length) */
  tot_len_words= 4 + tot_partition_words + tot_name_words;
  tot_len_byte= PAR_WORD_SIZE * tot_len_words;
  file_buffer= (uchar *) my_alloca(tot_len_byte);
  if (!file_buffer)
    DBUG_RETURN(TRUE);
  bzero(file_buffer, tot_len_byte);
  engine_array= (file_buffer + PAR_ENGINES_OFFSET);
  name_buffer_ptr= (char*) (engine_array + tot_partition_words * PAR_WORD_SIZE
                            + PAR_WORD_SIZE);
  part_it.rewind();
  for (i= 0; i < no_parts; i++)
  {
    part_elem= part_it++;
    if (part_elem->part_state != PART_NORMAL &&
        part_elem->part_state != PART_TO_BE_ADDED &&
        part_elem->part_state != PART_CHANGED)
      continue;
    if (!m_is_sub_partitioned)
    {
      tablename_to_filename(part_elem->partition_name, part_name, FN_REFLEN);
      name_buffer_ptr= strmov(name_buffer_ptr, part_name)+1;
      *engine_array= (uchar) ha_legacy_type(part_elem->engine_type);
      DBUG_PRINT("info", ("engine: %u", *engine_array));
      engine_array++;
    }
    else
    {
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->no_subparts; j++)
      {
	subpart_elem= sub_it++;
        tablename_to_filename(part_elem->partition_name, part_name,
                              FN_REFLEN);
        tablename_to_filename(subpart_elem->partition_name, subpart_name,
                              FN_REFLEN);
	name_buffer_ptr+= name_add(name_buffer_ptr,
				   part_name,
				   subpart_name);
        *engine_array= (uchar) ha_legacy_type(subpart_elem->engine_type);
        DBUG_PRINT("info", ("engine: %u", *engine_array));
	engine_array++;
      }
    }
  }
  chksum= 0;
  int4store(file_buffer, tot_len_words);
  int4store(file_buffer + PAR_NUM_PARTS_OFFSET, tot_parts);
  int4store(file_buffer + PAR_ENGINES_OFFSET +
            (tot_partition_words * PAR_WORD_SIZE),
            tot_name_len);
  for (i= 0; i < tot_len_words; i++)
    chksum^= uint4korr(file_buffer + PAR_WORD_SIZE * i);
  int4store(file_buffer + PAR_CHECKSUM_OFFSET, chksum);
  /*
    Add .par extension to the file name.
    Create and write and close file
    to be used at open, delete_table and rename_table
  */
  fn_format(file_name, name, "", ha_par_ext, MY_APPEND_EXT);
  if ((file= my_create(file_name, CREATE_MODE, O_RDWR | O_TRUNC,
		       MYF(MY_WME))) >= 0)
  {
    result= my_write(file, (uchar *) file_buffer, tot_len_byte,
                     MYF(MY_WME | MY_NABP)) != 0;

    /* Write connection information (for federatedx engine) */
    part_it.rewind();
    for (i= 0; i < no_parts && !result; i++)
    {
      uchar buffer[4];
      part_elem= part_it++;
      uint length = part_elem->connect_string.length;
      int4store(buffer, length);
      if (my_write(file, buffer, 4, MYF(MY_WME | MY_NABP)) ||
          my_write(file, (uchar *) part_elem->connect_string.str, length,
                   MYF(MY_WME | MY_NABP)))
      {
        result= TRUE;
        break;
      }
    }
    VOID(my_close(file, MYF(0)));
  }
  else
    result= TRUE;
  my_afree((char*) file_buffer);
  DBUG_RETURN(result);
}


/**
  Clear handler variables and free some memory
*/

void ha_partition::clear_handler_file()
{
  if (m_engine_array)
    plugin_unlock_list(NULL, m_engine_array, m_tot_parts);
  free_root(&m_mem_root, MYF(MY_KEEP_PREALLOC));
  m_file_buffer= NULL;
  m_engine_array= NULL;
  m_connect_string= NULL;
}


/**
  Create underlying handler objects

  @param mem_root  Allocate memory through this

  @return Operation status
    @retval TRUE   Error
    @retval FALSE  Success
*/

bool ha_partition::create_handlers(MEM_ROOT *mem_root)
{
  uint i;
  uint alloc_len= (m_tot_parts + 1) * sizeof(handler*);
  handlerton *hton0;
  DBUG_ENTER("create_handlers");

  if (!(m_file= (handler **) alloc_root(mem_root, alloc_len)))
    DBUG_RETURN(TRUE);
  m_file_tot_parts= m_tot_parts;
  bzero((char*) m_file, alloc_len);
  for (i= 0; i < m_tot_parts; i++)
  {
    handlerton *hton= plugin_data(m_engine_array[i], handlerton*);
    if (!(m_file[i]= get_new_handler(table_share, mem_root,
                                     hton)))
      DBUG_RETURN(TRUE);
    DBUG_PRINT("info", ("engine_type: %u", hton->db_type));
  }
  /* For the moment we only support partition over the same table engine */
  hton0= plugin_data(m_engine_array[0], handlerton*);
  if (hton0 == myisam_hton)
  {
    DBUG_PRINT("info", ("MyISAM"));
    m_myisam= TRUE;
  }
  /* INNODB may not be compiled in... */
  else if (ha_legacy_type(hton0) == DB_TYPE_INNODB)
  {
    DBUG_PRINT("info", ("InnoDB"));
    m_innodb= TRUE;
  }
  DBUG_RETURN(FALSE);
}


/*
  Create underlying handler objects from partition info

  SYNOPSIS
    new_handlers_from_part_info()
    mem_root		Allocate memory through this

  RETURN VALUE
    TRUE                  Error
    FALSE                 Success
*/

bool ha_partition::new_handlers_from_part_info(MEM_ROOT *mem_root)
{
  uint i, j, part_count;
  partition_element *part_elem;
  uint alloc_len= (m_tot_parts + 1) * sizeof(handler*);
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);
  DBUG_ENTER("ha_partition::new_handlers_from_part_info");

  if (!(m_file= (handler **) alloc_root(mem_root, alloc_len)))
  {
    mem_alloc_error(alloc_len);
    goto error_end;
  }
  m_file_tot_parts= m_tot_parts;
  bzero((char*) m_file, alloc_len);
  DBUG_ASSERT(m_part_info->no_parts > 0);

  i= 0;
  part_count= 0;
  /*
    Don't know the size of the underlying storage engine, invent a number of
    bytes allocated for error message if allocation fails
  */
  do
  {
    part_elem= part_it++;
    if (m_is_sub_partitioned)
    {
      for (j= 0; j < m_part_info->no_subparts; j++)
      {
	if (!(m_file[part_count++]= get_new_handler(table_share, mem_root,
                                                    part_elem->engine_type)))
          goto error;
	DBUG_PRINT("info", ("engine_type: %u",
                   (uint) ha_legacy_type(part_elem->engine_type)));
      }
    }
    else
    {
      if (!(m_file[part_count++]= get_new_handler(table_share, mem_root,
                                                  part_elem->engine_type)))
        goto error;
      DBUG_PRINT("info", ("engine_type: %u",
                 (uint) ha_legacy_type(part_elem->engine_type)));
    }
  } while (++i < m_part_info->no_parts);
  if (part_elem->engine_type == myisam_hton)
  {
    DBUG_PRINT("info", ("MyISAM"));
    m_myisam= TRUE;
  }
  DBUG_RETURN(FALSE);
error:
  mem_alloc_error(sizeof(handler));
error_end:
  DBUG_RETURN(TRUE);
}


/**
  Read the .par file to get the partitions engines and names

  @param name  Name of table file (without extention)

  @return Operation status
    @retval true   Failure
    @retval false  Success

  @note On success, m_file_buffer is allocated and must be
  freed by the caller. m_name_buffer_ptr and m_tot_parts is also set.
*/

bool ha_partition::read_par_file(const char *name)
{
  char buff[FN_REFLEN], *tot_name_len_offset;
  File file;
  char *file_buffer;
  uint i, len_bytes, len_words, tot_partition_words, tot_name_words, chksum;
  DBUG_ENTER("ha_partition::read_par_file");
  DBUG_PRINT("enter", ("table name: '%s'", name));

  if (m_file_buffer)
    DBUG_RETURN(false);
  fn_format(buff, name, "", ha_par_ext, MY_APPEND_EXT);

  /* Following could be done with my_stat to read in whole file */
  if ((file= my_open(buff, O_RDONLY | O_SHARE, MYF(0))) < 0)
    DBUG_RETURN(true);
  if (my_read(file, (uchar *) & buff[0], PAR_WORD_SIZE, MYF(MY_NABP)))
    goto err1;
  len_words= uint4korr(buff);
  len_bytes= PAR_WORD_SIZE * len_words;
  if (my_seek(file, 0, MY_SEEK_SET, MYF(0)) == MY_FILEPOS_ERROR)
    goto err1;
  if (!(file_buffer= (char*) alloc_root(&m_mem_root, len_bytes)))
    goto err1;
  if (my_read(file, (uchar *) file_buffer, len_bytes, MYF(MY_NABP)))
    goto err2;

  chksum= 0;
  for (i= 0; i < len_words; i++)
    chksum ^= uint4korr((file_buffer) + PAR_WORD_SIZE * i);
  if (chksum)
    goto err2;
  m_tot_parts= uint4korr((file_buffer) + PAR_NUM_PARTS_OFFSET);
  DBUG_PRINT("info", ("No of parts = %u", m_tot_parts));
  tot_partition_words= (m_tot_parts + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;

  tot_name_len_offset= file_buffer + PAR_ENGINES_OFFSET +
                       PAR_WORD_SIZE * tot_partition_words;
  tot_name_words= (uint4korr(tot_name_len_offset) + PAR_WORD_SIZE - 1) /
                  PAR_WORD_SIZE;
  /*
    Verify the total length = tot size word, checksum word, num parts word +
    engines array + name length word + name array.
  */
  if (len_words != (tot_partition_words + tot_name_words + 4))
    goto err2;
  m_file_buffer= file_buffer;          // Will be freed in clear_handler_file()
  m_name_buffer_ptr= tot_name_len_offset + PAR_WORD_SIZE;

  if (!(m_connect_string= (LEX_STRING*)
        alloc_root(&m_mem_root, m_tot_parts * sizeof(LEX_STRING))))
    goto err2;
  bzero(m_connect_string, m_tot_parts * sizeof(LEX_STRING));

  /* Read connection arguments (for federated X engine) */
  for (i= 0; i < m_tot_parts; i++)
  {
    LEX_STRING connect_string;
    uchar buffer[4];
    if (my_read(file, buffer, 4, MYF(MY_NABP)))
    {
      /* No extra options; Probably not a federatedx engine */
      break;
    }
    connect_string.length= uint4korr(buffer);
    connect_string.str= (char*) alloc_root(&m_mem_root, connect_string.length+1);
    if (my_read(file, (uchar*) connect_string.str, connect_string.length,
                MYF(MY_NABP)))
      break;
    connect_string.str[connect_string.length]= 0;
    m_connect_string[i]= connect_string;
  }

  VOID(my_close(file, MYF(0)));
  DBUG_RETURN(false);

err2:
err1:
  VOID(my_close(file, MYF(0)));
  DBUG_RETURN(true);
}


/**
  Setup m_engine_array

  @param mem_root  MEM_ROOT to use for allocating new handlers

  @return Operation status
    @retval false  Success
    @retval true   Failure
*/

bool ha_partition::setup_engine_array(MEM_ROOT *mem_root)
{
  uint i;
  uchar *buff;
  handlerton **engine_array;

  DBUG_ASSERT(!m_file);
  DBUG_ENTER("ha_partition::setup_engine_array");
  engine_array= (handlerton **) my_alloca(m_tot_parts * sizeof(handlerton*));
  if (!engine_array)
    DBUG_RETURN(true);

  buff= (uchar *) (m_file_buffer + PAR_ENGINES_OFFSET);
  for (i= 0; i < m_tot_parts; i++)
  {
    engine_array[i]= ha_resolve_by_legacy_type(ha_thd(),
                                               (enum legacy_db_type)
                                                 *(buff + i));
    if (!engine_array[i])
      goto err;
  }
  if (!(m_engine_array= (plugin_ref*)
        alloc_root(&m_mem_root, m_tot_parts * sizeof(plugin_ref))))
    goto err;

  for (i= 0; i < m_tot_parts; i++)
    m_engine_array[i]= ha_lock_engine(NULL, engine_array[i]);

  my_afree((gptr) engine_array);
    
  if (create_handlers(mem_root))
  {
    clear_handler_file();
    DBUG_RETURN(true);
  }

  DBUG_RETURN(false);

err:
  my_afree((gptr) engine_array);
  DBUG_RETURN(true);
}


/**
  Get info about partition engines and their names from the .par file

  @param name      Full path of table name
  @param mem_root  Allocate memory through this
  @param is_clone  If it is a clone, don't create new handlers

  @return Operation status
    @retval true   Error
    @retval false  Success

  @note Open handler file to get partition names, engine types and number of
  partitions.
*/

bool ha_partition::get_from_handler_file(const char *name, MEM_ROOT *mem_root,
                                         bool is_clone)
{
  DBUG_ENTER("ha_partition::get_from_handler_file");
  DBUG_PRINT("enter", ("table name: '%s'", name));

  if (m_file_buffer)
    DBUG_RETURN(false);

  if (read_par_file(name))
    DBUG_RETURN(true);

  if (!is_clone && setup_engine_array(mem_root))
    DBUG_RETURN(true);

  DBUG_RETURN(false);
}


/****************************************************************************
                MODULE open/close object
****************************************************************************/


/**
  A destructor for partition-specific TABLE_SHARE data.
*/

void ha_data_partition_destroy(void *ha_data)
{
  if (ha_data)
  {
    HA_DATA_PARTITION *ha_part_data= (HA_DATA_PARTITION*) ha_data;
    pthread_mutex_destroy(&ha_part_data->LOCK_auto_inc);
  }
}

/*
  Open handler object

  SYNOPSIS
    open()
    name                  Full path of table name
    mode                  Open mode flags
    test_if_locked        ?

  RETURN VALUE
    >0                    Error
    0                     Success

  DESCRIPTION
    Used for opening tables. The name will be the name of the file.
    A table is opened when it needs to be opened. For instance
    when a request comes in for a select on the table (tables are not
    open and closed for each request, they are cached).

    Called from handler.cc by handler::ha_open(). The server opens all tables
    by calling ha_open() which then calls the handler specific open().
*/

int ha_partition::open(const char *name, int mode, uint test_if_locked)
{
  char *name_buffer_ptr;
  int error= HA_ERR_INITIALIZATION;
  uint alloc_len;
  handler **file;
  char name_buff[FN_REFLEN];
  bool is_not_tmp_table= (table_share->tmp_table == NO_TMP_TABLE);
  ulonglong check_table_flags;
  DBUG_ENTER("ha_partition::open");

  DBUG_ASSERT(table->s == table_share);
  ref_length= 0;
  m_mode= mode;
  m_open_test_lock= test_if_locked;
  m_part_field_array= m_part_info->full_part_field_array;
  if (get_from_handler_file(name, &table->mem_root, test(m_is_clone_of)))
    DBUG_RETURN(error);
  name_buffer_ptr= m_name_buffer_ptr;
  m_start_key.length= 0;
  m_rec0= table->record[0];
  m_rec_length= table_share->reclength;
  alloc_len= m_tot_parts * (m_rec_length + PARTITION_BYTES_IN_POS);
  alloc_len+= table_share->max_key_length;
  if (!m_ordered_rec_buffer)
  {
    if (!(m_ordered_rec_buffer= (uchar*)my_malloc(alloc_len, MYF(MY_WME))))
    {
      DBUG_RETURN(error);
    }
    {
      /*
        We set-up one record per partition and each record has 2 bytes in
        front where the partition id is written. This is used by ordered
        index_read.
        We also set-up a reference to the first record for temporary use in
        setting up the scan.
      */
      char *ptr= (char*)m_ordered_rec_buffer;
      uint i= 0;
      do
      {
        int2store(ptr, i);
        ptr+= m_rec_length + PARTITION_BYTES_IN_POS;
      } while (++i < m_tot_parts);
      m_start_key.key= (const uchar*)ptr;
    }
  }

  /* Initialize the bitmap we use to minimize ha_start_bulk_insert calls */
  if (bitmap_init(&m_bulk_insert_started, NULL, m_tot_parts + 1, FALSE))
    DBUG_RETURN(error);
  bitmap_clear_all(&m_bulk_insert_started);
  /* Initialize the bitmap we use to determine what partitions are used */
  if (!m_is_clone_of)
  {
    DBUG_ASSERT(!m_clone_mem_root);
    if (bitmap_init(&(m_part_info->used_partitions), NULL, m_tot_parts, TRUE))
    {
      bitmap_free(&m_bulk_insert_started);
      DBUG_RETURN(error);
    }
    bitmap_set_all(&(m_part_info->used_partitions));
  }

  if (m_is_clone_of)
  {
    uint i;
    DBUG_ASSERT(m_clone_mem_root);
    /* Allocate an array of handler pointers for the partitions handlers. */
    alloc_len= (m_tot_parts + 1) * sizeof(handler*);
    if (!(m_file= (handler **) alloc_root(m_clone_mem_root, alloc_len)))
      goto err_alloc;
    memset(m_file, 0, alloc_len);
    /*
      Populate them by cloning the original partitions. This also opens them.
      Note that file->ref is allocated too.
    */
    file= m_is_clone_of->m_file;
    for (i= 0; i < m_tot_parts; i++)
    {
      create_partition_name(name_buff, name, name_buffer_ptr, NORMAL_PART_NAME,
                            FALSE);
      if (!(m_file[i]= file[i]->clone(name_buff, m_clone_mem_root)))
      {
        error= HA_ERR_INITIALIZATION;
        file= &m_file[i];
        goto err_handler;
      }
      name_buffer_ptr+= strlen(name_buffer_ptr) + 1;
    }
  }
  else
  {
   file= m_file;
   do
   {
      create_partition_name(name_buff, name, name_buffer_ptr, NORMAL_PART_NAME,
                            FALSE);
      table->s->connect_string = m_connect_string[(uint)(file-m_file)];
      if ((error= (*file)->ha_open(table, name_buff, mode, test_if_locked)))
        goto err_handler;
      bzero(&table->s->connect_string, sizeof(LEX_STRING));
      m_no_locks+= (*file)->lock_count();
      name_buffer_ptr+= strlen(name_buffer_ptr) + 1;
    } while (*(++file));
  }
  
  file= m_file;
  ref_length= (*file)->ref_length;
  check_table_flags= (((*file)->ha_table_flags() &
                       ~(PARTITION_DISABLED_TABLE_FLAGS)) |
                      (PARTITION_ENABLED_TABLE_FLAGS));
  while (*(++file))
  {
    /* MyISAM can have smaller ref_length for partitions with MAX_ROWS set */
    set_if_bigger(ref_length, ((*file)->ref_length));
    /*
      Verify that all partitions have the same set of table flags.
      Mask all flags that partitioning enables/disables.
    */
    if (check_table_flags != (((*file)->ha_table_flags() &
                               ~(PARTITION_DISABLED_TABLE_FLAGS)) |
                              (PARTITION_ENABLED_TABLE_FLAGS)))
    {
      error= HA_ERR_INITIALIZATION;
      /* set file to last handler, so all of them is closed */
      file = &m_file[m_tot_parts - 1];
      goto err_handler;
    }
  }
  key_used_on_scan= m_file[0]->key_used_on_scan;
  implicit_emptied= m_file[0]->implicit_emptied;
  /*
    Add 2 bytes for partition id in position ref length.
    ref_length=max_in_all_partitions(ref_length) + PARTITION_BYTES_IN_POS
  */
  ref_length+= PARTITION_BYTES_IN_POS;
  m_ref_length= ref_length;

  /*
    Release buffer read from .par file. It will not be reused again after
    being opened once.
  */
  clear_handler_file();
  /*
    Initialize priority queue, initialized to reading forward.
  */
  if ((error= init_queue(&m_queue, m_tot_parts, (uint) PARTITION_BYTES_IN_POS,
                         0, key_rec_cmp, (void*)this)))
    goto err_handler;

  /*
    Use table_share->ha_data to share auto_increment_value among all handlers
    for the same table.
  */
  if (is_not_tmp_table)
    pthread_mutex_lock(&table_share->mutex);
  if (!table_share->ha_data)
  {
    HA_DATA_PARTITION *ha_data;
    /* currently only needed for auto_increment */
    table_share->ha_data= ha_data= (HA_DATA_PARTITION*)
                                   alloc_root(&table_share->mem_root,
                                              sizeof(HA_DATA_PARTITION));
    if (!ha_data)
    {
      if (is_not_tmp_table)
        pthread_mutex_unlock(&table_share->mutex);
      goto err_handler;
    }
    DBUG_PRINT("info", ("table_share->ha_data 0x%p", ha_data));
    bzero(ha_data, sizeof(HA_DATA_PARTITION));
    table_share->ha_data_destroy= ha_data_partition_destroy;
    VOID(pthread_mutex_init(&ha_data->LOCK_auto_inc, MY_MUTEX_INIT_FAST));
  }
  if (is_not_tmp_table)
    pthread_mutex_unlock(&table_share->mutex);
  /*
    Some handlers update statistics as part of the open call. This will in
    some cases corrupt the statistics of the partition handler and thus
    to ensure we have correct statistics we call info from open after
    calling open on all individual handlers.
  */
  m_handler_status= handler_opened;
  if (m_part_info->part_expr)
    m_part_func_monotonicity_info=
                            m_part_info->part_expr->get_monotonicity_info();
  else if (m_part_info->list_of_part_fields)
    m_part_func_monotonicity_info= MONOTONIC_STRICT_INCREASING;
  info(HA_STATUS_VARIABLE | HA_STATUS_CONST);
  DBUG_RETURN(0);

err_handler:
  DEBUG_SYNC(ha_thd(), "partition_open_error");
  while (file-- != m_file)
    (*file)->close();
err_alloc:
  bitmap_free(&m_bulk_insert_started);
  if (!m_is_clone_of)
    bitmap_free(&(m_part_info->used_partitions));

  DBUG_RETURN(error);
}


/**
  Clone the open and locked partitioning handler.

  @param  mem_root  MEM_ROOT to use.

  @return Pointer to the successfully created clone or NULL

  @details
  This function creates a new ha_partition handler as a clone/copy. The
  original (this) must already be opened and locked. The clone will use
  the originals m_part_info.
  It also allocates memory for ref + ref_dup.
  In ha_partition::open() it will clone its original handlers partitions
  which will allocate then on the correct MEM_ROOT and also open them.
*/

handler *ha_partition::clone(const char *name, MEM_ROOT *mem_root)
{
  ha_partition *new_handler;

  DBUG_ENTER("ha_partition::clone");
  new_handler= new (mem_root) ha_partition(ht, table_share, m_part_info,
                                           this, mem_root);
  /*
    Allocate new_handler->ref here because otherwise ha_open will allocate it
    on this->table->mem_root and we will not be able to reclaim that memory 
    when the clone handler object is destroyed.
  */
  if (new_handler &&
      !(new_handler->ref= (uchar*) alloc_root(mem_root,
                                              ALIGN_SIZE(m_ref_length)*2)))
    new_handler= NULL;

  if (new_handler &&
      new_handler->ha_open(table, name,
                           table->db_stat, HA_OPEN_IGNORE_IF_LOCKED))
    new_handler= NULL;

  DBUG_RETURN((handler*) new_handler);
}


/*
  Close handler object

  SYNOPSIS
    close()

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    Called from sql_base.cc, sql_select.cc, and table.cc.
    In sql_select.cc it is only used to close up temporary tables or during
    the process where a temporary table is converted over to being a
    myisam table.
    For sql_base.cc look at close_data_tables().
*/

int ha_partition::close(void)
{
  bool first= TRUE;
  handler **file;
  DBUG_ENTER("ha_partition::close");

  DBUG_ASSERT(table->s == table_share);
  delete_queue(&m_queue);
  bitmap_free(&m_bulk_insert_started);
  if (!m_is_clone_of)
    bitmap_free(&(m_part_info->used_partitions));
  file= m_file;

repeat:
  do
  {
    (*file)->close();
  } while (*(++file));

  if (first && m_added_file && m_added_file[0])
  {
    file= m_added_file;
    first= FALSE;
    goto repeat;
  }

  m_handler_status= handler_closed;
  DBUG_RETURN(0);
}

/****************************************************************************
                MODULE start/end statement
****************************************************************************/
/*
  A number of methods to define various constants for the handler. In
  the case of the partition handler we need to use some max and min
  of the underlying handlers in most cases.
*/

/*
  Set external locks on table

  SYNOPSIS
    external_lock()
    thd                    Thread object
    lock_type              Type of external lock

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    First you should go read the section "locking functions for mysql" in
    lock.cc to understand this.
    This create a lock on the table. If you are implementing a storage engine
    that can handle transactions look at ha_berkeley.cc to see how you will
    want to go about doing this. Otherwise you should consider calling
    flock() here.
    Originally this method was used to set locks on file level to enable
    several MySQL Servers to work on the same data. For transactional
    engines it has been "abused" to also mean start and end of statements
    to enable proper rollback of statements and transactions. When LOCK
    TABLES has been issued the start_stmt method takes over the role of
    indicating start of statement but in this case there is no end of
    statement indicator(?).

    Called from lock.cc by lock_external() and unlock_external(). Also called
    from sql_table.cc by copy_data_between_tables().
*/

int ha_partition::external_lock(THD *thd, int lock_type)
{
  bool first= TRUE;
  uint error;
  handler **file;
  DBUG_ENTER("ha_partition::external_lock");

  DBUG_ASSERT(!auto_increment_lock && !auto_increment_safe_stmt_log_lock);
  file= m_file;
  m_lock_type= lock_type;

repeat:
  do
  {
    DBUG_PRINT("info", ("external_lock(thd, %d) iteration %d",
                        lock_type, (int) (file - m_file)));
    if ((error= (*file)->ha_external_lock(thd, lock_type)))
    {
      if (F_UNLCK != lock_type)
        goto err_handler;
    }
  } while (*(++file));

  if (first && m_added_file && m_added_file[0])
  {
    DBUG_ASSERT(lock_type == F_UNLCK);
    file= m_added_file;
    first= FALSE;
    goto repeat;
  }
  DBUG_RETURN(0);

err_handler:
  while (file-- != m_file)
  {
    (*file)->ha_external_lock(thd, F_UNLCK);
  }
  DBUG_RETURN(error);
}


/*
  Get the lock(s) for the table and perform conversion of locks if needed

  SYNOPSIS
    store_lock()
    thd                   Thread object
    to                    Lock object array
    lock_type             Table lock type

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    The idea with handler::store_lock() is the following:

    The statement decided which locks we should need for the table
    for updates/deletes/inserts we get WRITE locks, for SELECT... we get
    read locks.

    Before adding the lock into the table lock handler (see thr_lock.c)
    mysqld calls store lock with the requested locks.  Store lock can now
    modify a write lock to a read lock (or some other lock), ignore the
    lock (if we don't want to use MySQL table locks at all) or add locks
    for many tables (like we do when we are using a MERGE handler).

    Berkeley DB for partition  changes all WRITE locks to TL_WRITE_ALLOW_WRITE
    (which signals that we are doing WRITES, but we are still allowing other
    reader's and writer's.

    When releasing locks, store_lock() is also called. In this case one
    usually doesn't have to do anything.

    store_lock is called when holding a global mutex to ensure that only
    one thread at a time changes the locking information of tables.

    In some exceptional cases MySQL may send a request for a TL_IGNORE;
    This means that we are requesting the same lock as last time and this
    should also be ignored. (This may happen when someone does a flush
    table when we have opened a part of the tables, in which case mysqld
    closes and reopens the tables and tries to get the same locks as last
    time).  In the future we will probably try to remove this.

    Called from lock.cc by get_lock_data().
*/

THR_LOCK_DATA **ha_partition::store_lock(THD *thd,
					 THR_LOCK_DATA **to,
					 enum thr_lock_type lock_type)
{
  handler **file;
  DBUG_ENTER("ha_partition::store_lock");
  file= m_file;
  do
  {
    DBUG_PRINT("info", ("store lock %d iteration", (int) (file - m_file)));
    to= (*file)->store_lock(thd, to, lock_type);
  } while (*(++file));
  DBUG_RETURN(to);
}

/*
  Start a statement when table is locked

  SYNOPSIS
    start_stmt()
    thd                  Thread object
    lock_type            Type of external lock

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    This method is called instead of external lock when the table is locked
    before the statement is executed.
*/

int ha_partition::start_stmt(THD *thd, thr_lock_type lock_type)
{
  int error= 0;
  handler **file;
  DBUG_ENTER("ha_partition::start_stmt");

  file= m_file;
  do
  {
    if ((error= (*file)->start_stmt(thd, lock_type)))
      break;
  } while (*(++file));
  DBUG_RETURN(error);
}


/*
  Get number of lock objects returned in store_lock

  SYNOPSIS
    lock_count()

  RETURN VALUE
    Number of locks returned in call to store_lock

  DESCRIPTION
    Returns the number of store locks needed in call to store lock.
    We return number of partitions since we call store_lock on each
    underlying handler. Assists the above functions in allocating
    sufficient space for lock structures.
*/

uint ha_partition::lock_count() const
{
  DBUG_ENTER("ha_partition::lock_count");
  DBUG_PRINT("info", ("m_no_locks %d", m_no_locks));
  DBUG_RETURN(m_no_locks);
}


/*
  Unlock last accessed row

  SYNOPSIS
    unlock_row()

  RETURN VALUE
    NONE

  DESCRIPTION
    Record currently processed was not in the result set of the statement
    and is thus unlocked. Used for UPDATE and DELETE queries.
*/

void ha_partition::unlock_row()
{
  DBUG_ENTER("ha_partition::unlock_row");
  m_file[m_last_part]->unlock_row();
  DBUG_VOID_RETURN;
}

/**
  Check if semi consistent read was used

  SYNOPSIS
    was_semi_consistent_read()

  RETURN VALUE
    TRUE   Previous read was a semi consistent read
    FALSE  Previous read was not a semi consistent read

  DESCRIPTION
    See handler.h:
    In an UPDATE or DELETE, if the row under the cursor was locked by another
    transaction, and the engine used an optimistic read of the last
    committed row value under the cursor, then the engine returns 1 from this
    function. MySQL must NOT try to update this optimistic value. If the
    optimistic value does not match the WHERE condition, MySQL can decide to
    skip over this row. Currently only works for InnoDB. This can be used to
    avoid unnecessary lock waits.

    If this method returns nonzero, it will also signal the storage
    engine that the next read will be a locking re-read of the row.
*/
bool ha_partition::was_semi_consistent_read()
{
  DBUG_ENTER("ha_partition::was_semi_consistent_read");
  DBUG_ASSERT(m_last_part < m_tot_parts &&
              bitmap_is_set(&(m_part_info->used_partitions), m_last_part));
  DBUG_RETURN(m_file[m_last_part]->was_semi_consistent_read());
}

/**
  Use semi consistent read if possible

  SYNOPSIS
    try_semi_consistent_read()
    yes   Turn on semi consistent read

  RETURN VALUE
    NONE

  DESCRIPTION
    See handler.h:
    Tell the engine whether it should avoid unnecessary lock waits.
    If yes, in an UPDATE or DELETE, if the row under the cursor was locked
    by another transaction, the engine may try an optimistic read of
    the last committed row value under the cursor.
    Note: prune_partitions are already called before this call, so using
    pruning is OK.
*/
void ha_partition::try_semi_consistent_read(bool yes)
{
  handler **file;
  DBUG_ENTER("ha_partition::try_semi_consistent_read");
  
  for (file= m_file; *file; file++)
  {
    if (bitmap_is_set(&(m_part_info->used_partitions), (file - m_file)))
      (*file)->try_semi_consistent_read(yes);
  }
  DBUG_VOID_RETURN;
}


/****************************************************************************
                MODULE change record
****************************************************************************/

/*
  Insert a row to the table

  SYNOPSIS
    write_row()
    buf                        The row in MySQL Row Format

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    write_row() inserts a row. buf() is a byte array of data, normally
    record[0].

    You can use the field information to extract the data from the native byte
    array type.

    Example of this would be:
    for (Field **field=table->field ; *field ; field++)
    {
      ...
    }

    See ha_tina.cc for a variant of extracting all of the data as strings.
    ha_berkeley.cc has a variant of how to store it intact by "packing" it
    for ha_berkeley's own native storage type.

    Called from item_sum.cc, item_sum.cc, sql_acl.cc, sql_insert.cc,
    sql_insert.cc, sql_select.cc, sql_table.cc, sql_udf.cc, and sql_update.cc.

    ADDITIONAL INFO:

    We have to set timestamp fields and auto_increment fields, because those
    may be used in determining which partition the row should be written to.
*/

int ha_partition::write_row(uchar * buf)
{
  uint32 part_id;
  int error;
  longlong func_value;
  bool have_auto_increment= table->next_number_field && buf == table->record[0];
  my_bitmap_map *old_map;
  HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
  THD *thd= ha_thd();
  timestamp_auto_set_type saved_timestamp_type= table->timestamp_field_type;
  ulong saved_sql_mode= thd->variables.sql_mode;
  bool saved_auto_inc_field_not_null= table->auto_increment_field_not_null;
#ifdef NOT_NEEDED
  uchar *rec0= m_rec0;
#endif
  DBUG_ENTER("ha_partition::write_row");
  DBUG_ASSERT(buf == m_rec0);

  /* If we have a timestamp column, update it to the current time */
  if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_INSERT)
    table->timestamp_field->set_time();
  table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;

  /*
    If we have an auto_increment column and we are writing a changed row
    or a new row, then update the auto_increment value in the record.
  */
  if (have_auto_increment)
  {
    if (!ha_data->auto_inc_initialized &&
        !table->s->next_number_keypart)
    {
      /*
        If auto_increment in table_share is not initialized, start by
        initializing it.
      */
      info(HA_STATUS_AUTO);
    }
    error= update_auto_increment();

    /*
      If we have failed to set the auto-increment value for this row,
      it is highly likely that we will not be able to insert it into
      the correct partition. We must check and fail if neccessary.
    */
    if (error)
      goto exit;

    /*
      Don't allow generation of auto_increment value the partitions handler.
      If a partitions handler would change the value, then it might not
      match the partition any longer.
      This can occur if 'SET INSERT_ID = 0; INSERT (NULL)',
      So allow this by adding 'MODE_NO_AUTO_VALUE_ON_ZERO' to sql_mode.
      The partitions handler::next_insert_id must always be 0. Otherwise
      we need to forward release_auto_increment, or reset it for all
      partitions.
    */
    if (table->next_number_field->val_int() == 0)
    {
      table->auto_increment_field_not_null= TRUE;
      thd->variables.sql_mode|= MODE_NO_AUTO_VALUE_ON_ZERO;
    }
  }

  old_map= dbug_tmp_use_all_columns(table, table->read_set);
#ifdef NOT_NEEDED
  if (likely(buf == rec0))
#endif
    error= m_part_info->get_partition_id(m_part_info, &part_id,
                                         &func_value);
#ifdef NOT_NEEDED
  else
  {
    set_field_ptr(m_part_field_array, buf, rec0);
    error= m_part_info->get_partition_id(m_part_info, &part_id,
                                         &func_value);
    set_field_ptr(m_part_field_array, rec0, buf);
  }
#endif
  dbug_tmp_restore_column_map(table->read_set, old_map);
  if (unlikely(error))
  {
    m_part_info->err_value= func_value;
    goto exit;
  }
  m_last_part= part_id;
  DBUG_PRINT("info", ("Insert in partition %d", part_id));
  start_part_bulk_insert(thd, part_id);

  tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
  error= m_file[part_id]->ha_write_row(buf);
  if (have_auto_increment && !table->s->next_number_keypart)
    set_auto_increment_if_higher(table->next_number_field);
  reenable_binlog(thd);
exit:
  thd->variables.sql_mode= saved_sql_mode;
  table->auto_increment_field_not_null= saved_auto_inc_field_not_null;
  table->timestamp_field_type= saved_timestamp_type;
  DBUG_RETURN(error);
}


/*
  Update an existing row

  SYNOPSIS
    update_row()
    old_data                 Old record in MySQL Row Format
    new_data                 New record in MySQL Row Format

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    Yes, update_row() does what you expect, it updates a row. old_data will
    have the previous row record in it, while new_data will have the newest
    data in it.
    Keep in mind that the server can do updates based on ordering if an
    ORDER BY clause was used. Consecutive ordering is not guarenteed.

    Called from sql_select.cc, sql_acl.cc, sql_update.cc, and sql_insert.cc.
    new_data is always record[0]
    old_data is normally record[1] but may be anything
*/

int ha_partition::update_row(const uchar *old_data, uchar *new_data)
{
  THD *thd= ha_thd();
  uint32 new_part_id, old_part_id;
  int error= 0;
  longlong func_value;
  timestamp_auto_set_type orig_timestamp_type= table->timestamp_field_type;
  DBUG_ENTER("ha_partition::update_row");

  /*
    We need to set timestamp field once before we calculate
    the partition. Then we disable timestamp calculations
    inside m_file[*]->update_row() methods
  */
  if (orig_timestamp_type & TIMESTAMP_AUTO_SET_ON_UPDATE)
    table->timestamp_field->set_time();
  table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;

  if ((error= get_parts_for_update(old_data, new_data, table->record[0],
                                   m_part_info, &old_part_id, &new_part_id,
                                   &func_value)))
  {
    m_part_info->err_value= func_value;
    goto exit;
  }

  m_last_part= new_part_id;
  start_part_bulk_insert(thd, new_part_id);
  if (new_part_id == old_part_id)
  {
    DBUG_PRINT("info", ("Update in partition %d", new_part_id));
    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[new_part_id]->ha_update_row(old_data, new_data);
    reenable_binlog(thd);
    goto exit;
  }
  else
  {
    Field *saved_next_number_field= table->next_number_field;
    /*
      Don't allow generation of auto_increment value for update.
      table->next_number_field is never set on UPDATE.
      But is set for INSERT ... ON DUPLICATE KEY UPDATE,
      and since update_row() does not generate or update an auto_inc value,
      we cannot have next_number_field set when moving a row
      to another partition with write_row(), since that could
      generate/update the auto_inc value.
      This gives the same behavior for partitioned vs non partitioned tables.
    */
    table->next_number_field= NULL;
    DBUG_PRINT("info", ("Update from partition %d to partition %d",
			old_part_id, new_part_id));
    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[new_part_id]->ha_write_row(new_data);
    reenable_binlog(thd);
    table->next_number_field= saved_next_number_field;
    if (error)
      goto exit;

    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[old_part_id]->ha_delete_row(old_data);
    reenable_binlog(thd);
    if (error)
    {
#ifdef IN_THE_FUTURE
      (void) m_file[new_part_id]->delete_last_inserted_row(new_data);
#endif
      goto exit;
    }
  }

exit:
  /*
    If updating an auto_increment column, update
    table_share->ha_data->next_auto_inc_val if needed.
    (not to be used if auto_increment on secondary field in a multi-column
    index)
    mysql_update does not set table->next_number_field, so we use
    table->found_next_number_field instead.
    Also checking that the field is marked in the write set.
  */
  if (table->found_next_number_field &&
      new_data == table->record[0] &&
      !table->s->next_number_keypart &&
      bitmap_is_set(table->write_set,
                    table->found_next_number_field->field_index))
  {
    HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
    if (!ha_data->auto_inc_initialized)
      info(HA_STATUS_AUTO);
    set_auto_increment_if_higher(table->found_next_number_field);
  }
  table->timestamp_field_type= orig_timestamp_type;
  DBUG_RETURN(error);
}


/*
  Remove an existing row

  SYNOPSIS
    delete_row
    buf                      Deleted row in MySQL Row Format

  RETURN VALUE
    >0                       Error Code
    0                        Success

  DESCRIPTION
    This will delete a row. buf will contain a copy of the row to be deleted.
    The server will call this right after the current row has been read
    (from either a previous rnd_xxx() or index_xxx() call).
    If you keep a pointer to the last row or can access a primary key it will
    make doing the deletion quite a bit easier.
    Keep in mind that the server does no guarentee consecutive deletions.
    ORDER BY clauses can be used.

    Called in sql_acl.cc and sql_udf.cc to manage internal table information.
    Called in sql_delete.cc, sql_insert.cc, and sql_select.cc. In sql_select
    it is used for removing duplicates while in insert it is used for REPLACE
    calls.

    buf is either record[0] or record[1]
*/

int ha_partition::delete_row(const uchar *buf)
{
  uint32 part_id;
  int error;
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::delete_row");

  if ((error= get_part_for_delete(buf, m_rec0, m_part_info, &part_id)))
  {
    DBUG_RETURN(error);
  }
  m_last_part= part_id;
  tmp_disable_binlog(thd);
  error= m_file[part_id]->ha_delete_row(buf);
  reenable_binlog(thd);
  DBUG_RETURN(error);
}


/*
  Delete all rows in a table

  SYNOPSIS
    delete_all_rows()

  RETURN VALUE
    >0                       Error Code
    0                        Success

  DESCRIPTION
    Used to delete all rows in a table. Both for cases of truncate and
    for cases where the optimizer realizes that all rows will be
    removed as a result of a SQL statement.

    Called from item_sum.cc by Item_func_group_concat::clear(),
    Item_sum_count_distinct::clear(), and Item_func_group_concat::clear().
    Called from sql_delete.cc by mysql_delete().
    Called from sql_select.cc by JOIN::reinit().
    Called from sql_union.cc by st_select_lex_unit::exec().
*/

int ha_partition::delete_all_rows()
{
  int error;
  bool truncate= FALSE;
  handler **file;
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::delete_all_rows");

  if (thd->lex->sql_command == SQLCOM_TRUNCATE)
  {
    HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
    lock_auto_increment();
    ha_data->next_auto_inc_val= 0;
    ha_data->auto_inc_initialized= FALSE;
    unlock_auto_increment();
    truncate= TRUE;
  }
  file= m_file;
  do
  {
    if ((error= (*file)->ha_delete_all_rows()))
      DBUG_RETURN(error);
    /* Ignore the error */
    if (truncate)
      (void) (*file)->ha_reset_auto_increment(0);
  } while (*(++file));
  DBUG_RETURN(0);
}


/*
  Start a large batch of insert rows

  SYNOPSIS
    start_bulk_insert()
    rows                  Number of rows to insert

  RETURN VALUE
    NONE

  DESCRIPTION
    rows == 0 means we will probably insert many rows
*/
void ha_partition::start_bulk_insert(ha_rows rows)
{
  DBUG_ENTER("ha_partition::start_bulk_insert");

  m_bulk_inserted_rows= 0;
  bitmap_clear_all(&m_bulk_insert_started);
  /* use the last bit for marking if bulk_insert_started was called */
  bitmap_set_bit(&m_bulk_insert_started, m_tot_parts);
  DBUG_VOID_RETURN;
}


/*
  Check if start_bulk_insert has been called for this partition,
  if not, call it and mark it called
*/
void ha_partition::start_part_bulk_insert(THD *thd, uint part_id)
{
  long old_buffer_size;
  if (!bitmap_is_set(&m_bulk_insert_started, part_id) &&
      bitmap_is_set(&m_bulk_insert_started, m_tot_parts))
  {
    old_buffer_size= thd->variables.read_buff_size;
    /* Update read_buffer_size for this partition */
    thd->variables.read_buff_size= estimate_read_buffer_size(old_buffer_size);
    m_file[part_id]->ha_start_bulk_insert(guess_bulk_insert_rows());
    bitmap_set_bit(&m_bulk_insert_started, part_id);
    thd->variables.read_buff_size= old_buffer_size;
  }
  m_bulk_inserted_rows++;
}

/*
  Estimate the read buffer size for each partition.
  SYNOPSIS
    ha_partition::estimate_read_buffer_size()
    original_size  read buffer size originally set for the server
  RETURN VALUE
    estimated buffer size.
  DESCRIPTION
    If the estimated number of rows to insert is less than 10 (but not 0)
    the new buffer size is same as original buffer size.
    In case of first partition of when partition function is monotonic 
    new buffer size is same as the original buffer size.
    For rest of the partition total buffer of 10*original_size is divided 
    equally if number of partition is more than 10 other wise each partition
    will be allowed to use original buffer size.
*/
long ha_partition::estimate_read_buffer_size(long original_size)
{
  /*
    If number of rows to insert is less than 10, but not 0,
    return original buffer size.
  */
  if (estimation_rows_to_insert && (estimation_rows_to_insert < 10))
    return (original_size);
  /*
    If first insert/partition and monotonic partition function,
    allow using buffer size originally set.
   */
  if (!m_bulk_inserted_rows &&
      m_part_func_monotonicity_info != NON_MONOTONIC &&
      m_tot_parts > 1)
    return original_size;
  /*
    Allow total buffer used in all partition to go up to 10*read_buffer_size.
    11*read_buffer_size in case of monotonic partition function.
  */

  if (m_tot_parts < 10)
      return original_size;
  return (original_size * 10 / m_tot_parts);
}

/*
  Try to predict the number of inserts into this partition.

  If less than 10 rows (including 0 which means Unknown)
    just give that as a guess
  If monotonic partitioning function was used
    guess that 50 % of the inserts goes to the first partition
  For all other cases, guess on equal distribution between the partitions
*/ 
ha_rows ha_partition::guess_bulk_insert_rows()
{
  DBUG_ENTER("guess_bulk_insert_rows");

  if (estimation_rows_to_insert < 10)
    DBUG_RETURN(estimation_rows_to_insert);

  /* If first insert/partition and monotonic partition function, guess 50%.  */
  if (!m_bulk_inserted_rows && 
      m_part_func_monotonicity_info != NON_MONOTONIC &&
      m_tot_parts > 1)
    DBUG_RETURN(estimation_rows_to_insert / 2);

  /* Else guess on equal distribution (+1 is to avoid returning 0/Unknown) */
  if (m_bulk_inserted_rows < estimation_rows_to_insert)
    DBUG_RETURN(((estimation_rows_to_insert - m_bulk_inserted_rows)
                / m_tot_parts) + 1);
  /* The estimation was wrong, must say 'Unknown' */
  DBUG_RETURN(0);
}


/*
  Finish a large batch of insert rows

  SYNOPSIS
    end_bulk_insert()

  RETURN VALUE
    >0                      Error code
    0                       Success

  Note: end_bulk_insert can be called without start_bulk_insert
        being called, see bug#44108.

*/

int ha_partition::end_bulk_insert()
{
  int error= 0;
  uint i;
  DBUG_ENTER("ha_partition::end_bulk_insert");

  if (!bitmap_is_set(&m_bulk_insert_started, m_tot_parts))
    DBUG_RETURN(error);

  for (i= 0; i < m_tot_parts; i++)
  {
    int tmp;
    if (bitmap_is_set(&m_bulk_insert_started, i) &&
        (tmp= m_file[i]->ha_end_bulk_insert()))
      error= tmp;
  }
  bitmap_clear_all(&m_bulk_insert_started);
  DBUG_RETURN(error);
}


/****************************************************************************
                MODULE full table scan
****************************************************************************/
/*
  Initialize engine for random reads

  SYNOPSIS
    ha_partition::rnd_init()
    scan	0  Initialize for random reads through rnd_pos()
		1  Initialize for random scan through rnd_next()

  RETURN VALUE
    >0          Error code
    0           Success

  DESCRIPTION 
    rnd_init() is called when the server wants the storage engine to do a
    table scan or when the server wants to access data through rnd_pos.

    When scan is used we will scan one handler partition at a time.
    When preparing for rnd_pos we will init all handler partitions.
    No extra cache handling is needed when scannning is not performed.

    Before initialising we will call rnd_end to ensure that we clean up from
    any previous incarnation of a table scan.
    Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
    sql_table.cc, and sql_update.cc.
*/

int ha_partition::rnd_init(bool scan)
{
  int error;
  uint i= 0;
  uint32 part_id;
  DBUG_ENTER("ha_partition::rnd_init");

  /*
    For operations that may need to change data, we may need to extend
    read_set.
  */
  if (m_lock_type == F_WRLCK)
  {
    /*
      If write_set contains any of the fields used in partition and
      subpartition expression, we need to set all bits in read_set because
      the row may need to be inserted in a different [sub]partition. In
      other words update_row() can be converted into write_row(), which
      requires a complete record.
    */
    if (bitmap_is_overlapping(&m_part_info->full_part_field_set,
                              table->write_set))
      bitmap_set_all(table->read_set);
    else
    {
      /*
        Some handlers only read fields as specified by the bitmap for the
        read set. For partitioned handlers we always require that the
        fields of the partition functions are read such that we can
        calculate the partition id to place updated and deleted records.
      */
      bitmap_union(table->read_set, &m_part_info->full_part_field_set);
    }
  }

  /* Now we see what the index of our first important partition is */
  DBUG_PRINT("info", ("m_part_info->used_partitions: 0x%lx",
                      (long) m_part_info->used_partitions.bitmap));
  part_id= bitmap_get_first_set(&(m_part_info->used_partitions));
  DBUG_PRINT("info", ("m_part_spec.start_part %d", part_id));

  if (MY_BIT_NONE == part_id)
  {
    error= 0;
    goto err1;
  }

  /*
    We have a partition and we are scanning with rnd_next
    so we bump our cache
  */
  DBUG_PRINT("info", ("rnd_init on partition %d", part_id));
  if (scan)
  {
    /*
      rnd_end() is needed for partitioning to reset internal data if scan
      is already in use
    */
    rnd_end();
    late_extra_cache(part_id);
    if ((error= m_file[part_id]->ha_rnd_init(scan)))
      goto err;
  }
  else
  {
    for (i= part_id; i < m_tot_parts; i++)
    {
      if (bitmap_is_set(&(m_part_info->used_partitions), i))
      {
        if ((error= m_file[i]->ha_rnd_init(scan)))
          goto err;
      }
    }
  }
  m_scan_value= scan;
  m_part_spec.start_part= part_id;
  m_part_spec.end_part= m_tot_parts - 1;
  DBUG_PRINT("info", ("m_scan_value=%d", m_scan_value));
  DBUG_RETURN(0);

err:
  while ((int)--i >= (int)part_id)
  {
    if (bitmap_is_set(&(m_part_info->used_partitions), i))
      m_file[i]->ha_rnd_end();
  }
err1:
  m_scan_value= 2;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(error);
}


/*
  End of a table scan

  SYNOPSIS
    rnd_end()

  RETURN VALUE
    >0          Error code
    0           Success
*/

int ha_partition::rnd_end()
{
  handler **file;
  DBUG_ENTER("ha_partition::rnd_end");
  switch (m_scan_value) {
  case 2:                                       // Error
    break;
  case 1:
    if (NO_CURRENT_PART_ID != m_part_spec.start_part)         // Table scan
    {
      late_extra_no_cache(m_part_spec.start_part);
      m_file[m_part_spec.start_part]->ha_rnd_end();
    }
    break;
  case 0:
    file= m_file;
    do
    {
      if (bitmap_is_set(&(m_part_info->used_partitions), (file - m_file)))
        (*file)->ha_rnd_end();
    } while (*(++file));
    break;
  }
  m_scan_value= 2;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(0);
}

/*
  read next row during full table scan (scan in random row order)

  SYNOPSIS
    rnd_next()
    buf		buffer that should be filled with data

  RETURN VALUE
    >0          Error code
    0           Success

  DESCRIPTION
    This is called for each row of the table scan. When you run out of records
    you should return HA_ERR_END_OF_FILE.
    The Field structure for the table is the key to getting data into buf
    in a manner that will allow the server to understand it.

    Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
    sql_table.cc, and sql_update.cc.
*/

int ha_partition::rnd_next(uchar *buf)
{
  handler *file;
  int result= HA_ERR_END_OF_FILE;
  uint part_id= m_part_spec.start_part;
  DBUG_ENTER("ha_partition::rnd_next");

  if (NO_CURRENT_PART_ID == part_id)
  {
    /*
      The original set of partitions to scan was empty and thus we report
      the result here.
    */
    goto end;
  }
  
  DBUG_ASSERT(m_scan_value == 1);
  file= m_file[part_id];
  
  while (TRUE)
  {
    result= file->rnd_next(buf);
    if (!result)
    {
      m_last_part= part_id;
      m_part_spec.start_part= part_id;
      table->status= 0;
      DBUG_RETURN(0);
    }

    /*
      if we get here, then the current partition rnd_next returned failure
    */
    if (result == HA_ERR_RECORD_DELETED)
      continue;                               // Probably MyISAM

    if (result != HA_ERR_END_OF_FILE)
      goto end_dont_reset_start_part;         // Return error

    /* End current partition */
    late_extra_no_cache(part_id);
    DBUG_PRINT("info", ("rnd_end on partition %d", part_id));
    if ((result= file->ha_rnd_end()))
      break;
    
    /* Shift to next partition */
    while (++part_id < m_tot_parts &&
           !bitmap_is_set(&(m_part_info->used_partitions), part_id))
      ;
    if (part_id >= m_tot_parts)
    {
      result= HA_ERR_END_OF_FILE;
      break;
    }
    m_last_part= part_id;
    m_part_spec.start_part= part_id;
    file= m_file[part_id];
    DBUG_PRINT("info", ("rnd_init on partition %d", part_id));
    if ((result= file->ha_rnd_init(1)))
      break;
    late_extra_cache(part_id);
  }

end:
  m_part_spec.start_part= NO_CURRENT_PART_ID;
end_dont_reset_start_part:
  table->status= STATUS_NOT_FOUND;
  DBUG_RETURN(result);
}


/*
  Save position of current row

  SYNOPSIS
    position()
    record             Current record in MySQL Row Format

  RETURN VALUE
    NONE

  DESCRIPTION
    position() is called after each call to rnd_next() if the data needs
    to be ordered. You can do something like the following to store
    the position:
    ha_store_ptr(ref, ref_length, current_position);

    The server uses ref to store data. ref_length in the above case is
    the size needed to store current_position. ref is just a byte array
    that the server will maintain. If you are using offsets to mark rows, then
    current_position should be the offset. If it is a primary key like in
    BDB, then it needs to be a primary key.

    Called from filesort.cc, sql_select.cc, sql_delete.cc and sql_update.cc.
*/

void ha_partition::position(const uchar *record)
{
  handler *file= m_file[m_last_part];
  uint pad_length;
  DBUG_ENTER("ha_partition::position");

  file->position(record);
  int2store(ref, m_last_part);
  memcpy((ref + PARTITION_BYTES_IN_POS), file->ref, file->ref_length);
  pad_length= m_ref_length - PARTITION_BYTES_IN_POS - file->ref_length;
  if (pad_length)
    memset((ref + PARTITION_BYTES_IN_POS + file->ref_length), 0, pad_length);

#ifdef SUPPORTING_PARTITION_OVER_DIFFERENT_ENGINES
#ifdef HAVE_valgrind
  bzero(ref + PARTITION_BYTES_IN_POS + ref_length,
        max_ref_length-ref_length);
#endif /* HAVE_valgrind */
#endif
  DBUG_VOID_RETURN;
}


void ha_partition::column_bitmaps_signal()
{
    handler::column_bitmaps_signal();
    /* Must read all partition fields to make position() call possible */
    bitmap_union(table->read_set, &m_part_info->full_part_field_set);
}
 

/*
  Read row using position

  SYNOPSIS
    rnd_pos()
    out:buf                     Row read in MySQL Row Format
    position                    Position of read row

  RETURN VALUE
    >0                          Error code
    0                           Success

  DESCRIPTION
    This is like rnd_next, but you are given a position to use
    to determine the row. The position will be of the type that you stored in
    ref. You can use ha_get_ptr(pos,ref_length) to retrieve whatever key
    or position you saved when position() was called.
    Called from filesort.cc records.cc sql_insert.cc sql_select.cc
    sql_update.cc.
*/

int ha_partition::rnd_pos(uchar * buf, uchar *pos)
{
  uint part_id;
  handler *file;
  DBUG_ENTER("ha_partition::rnd_pos");

  part_id= uint2korr((const uchar *) pos);
  DBUG_ASSERT(part_id < m_tot_parts);
  file= m_file[part_id];
  m_last_part= part_id;
  DBUG_RETURN(file->rnd_pos(buf, (pos + PARTITION_BYTES_IN_POS)));
}


/*
  Read row using position using given record to find

  SYNOPSIS
    rnd_pos_by_record()
    record             Current record in MySQL Row Format

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    this works as position()+rnd_pos() functions, but does some extra work,
    calculating m_last_part - the partition to where the 'record'
    should go.

    called from replication (log_event.cc)
*/

int ha_partition::rnd_pos_by_record(uchar *record)
{
  DBUG_ENTER("ha_partition::rnd_pos_by_record");

  if (unlikely(get_part_for_delete(record, m_rec0, m_part_info, &m_last_part)))
    DBUG_RETURN(1);

  DBUG_RETURN(handler::rnd_pos_by_record(record));
}


/****************************************************************************
                MODULE index scan
****************************************************************************/
/*
  Positions an index cursor to the index specified in the handle. Fetches the
  row if available. If the key value is null, begin at the first key of the
  index.

  There are loads of optimisations possible here for the partition handler.
  The same optimisations can also be checked for full table scan although
  only through conditions and not from index ranges.
  Phase one optimisations:
    Check if the fields of the partition function are bound. If so only use
    the single partition it becomes bound to.
  Phase two optimisations:
    If it can be deducted through range or list partitioning that only a
    subset of the partitions are used, then only use those partitions.
*/

/*
  Initialize handler before start of index scan

  SYNOPSIS
    index_init()
    inx                Index number
    sorted             Is rows to be returned in sorted order

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_init is always called before starting index scans (except when
    starting through index_read_idx and using read_range variants).
*/

int ha_partition::index_init(uint inx, bool sorted)
{
  int error= 0;
  handler **file;
  DBUG_ENTER("ha_partition::index_init");

  DBUG_PRINT("info", ("inx %u sorted %u", inx, sorted));
  active_index= inx;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  m_start_key.length= 0;
  m_ordered= sorted;
  m_curr_key_info[0]= table->key_info+inx;
  if (m_pkey_is_clustered && table->s->primary_key != MAX_KEY)
  {
    /*
      if PK is clustered, then the key cmp must use the pk to
      differentiate between equal key in given index.
    */
    DBUG_PRINT("info", ("Clustered pk, using pk as secondary cmp"));
    m_curr_key_info[1]= table->key_info+table->s->primary_key;
    m_curr_key_info[2]= NULL;
  }
  else
    m_curr_key_info[1]= NULL;
  /*
    Some handlers only read fields as specified by the bitmap for the
    read set. For partitioned handlers we always require that the
    fields of the partition functions are read such that we can
    calculate the partition id to place updated and deleted records.
    But this is required for operations that may need to change data only.
  */
  if (m_lock_type == F_WRLCK)
    bitmap_union(table->read_set, &m_part_info->full_part_field_set);
  if (sorted)
  {
    /*
      An ordered scan is requested. We must make sure all fields of the 
      used index are in the read set, as partitioning requires them for
      sorting (see ha_partition::handle_ordered_index_scan).

      The SQL layer may request an ordered index scan without having index
      fields in the read set when
       - it needs to do an ordered scan over an index prefix.
       - it evaluates ORDER BY with SELECT COUNT(*) FROM t1.

      TODO: handle COUNT(*) queries via unordered scan.
    */
    uint i;
    KEY **key_info= m_curr_key_info;
    do
    {
      for (i= 0; i < (*key_info)->key_parts; i++)
        bitmap_set_bit(table->read_set,
                       (*key_info)->key_part[i].field->field_index);
    } while (*(++key_info));
  }
  file= m_file;
  do
  {
    /* TODO RONM: Change to index_init() when code is stable */
    if (bitmap_is_set(&(m_part_info->used_partitions), (file - m_file)))
      if ((error= (*file)->ha_index_init(inx, sorted)))
      {
        DBUG_ASSERT(0);                           // Should never happen
        break;
      }
  } while (*(++file));
  DBUG_RETURN(error);
}


/*
  End of index scan

  SYNOPSIS
    index_end()

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_end is called at the end of an index scan to clean up any
    things needed to clean up.
*/

int ha_partition::index_end()
{
  int error= 0;
  handler **file;
  DBUG_ENTER("ha_partition::index_end");

  active_index= MAX_KEY;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  file= m_file;
  do
  {
    int tmp;
    /* TODO RONM: Change to index_end() when code is stable */
    if (bitmap_is_set(&(m_part_info->used_partitions), (file - m_file)))
      if ((tmp= (*file)->ha_index_end()))
        error= tmp;
  } while (*(++file));
  DBUG_RETURN(error);
}


/*
  Read one record in an index scan and start an index scan

  SYNOPSIS
    index_read_map()
    buf                    Read row in MySQL Row Format
    key                    Key parts in consecutive order
    keypart_map            Which part of key is used
    find_flag              What type of key condition is used

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_read_map starts a new index scan using a start key. The MySQL Server
    will check the end key on its own. Thus to function properly the
    partitioned handler need to ensure that it delivers records in the sort
    order of the MySQL Server.
    index_read_map can be restarted without calling index_end on the previous
    index scan and without calling index_init. In this case the index_read_map
    is on the same index as the previous index_scan. This is particularly
    used in conjuntion with multi read ranges.
*/

int ha_partition::index_read_map(uchar *buf, const uchar *key,
                                 key_part_map keypart_map,
                                 enum ha_rkey_function find_flag)
{
  DBUG_ENTER("ha_partition::index_read_map");
  end_range= 0;
  m_index_scan_type= partition_index_read;
  m_start_key.key= key;
  m_start_key.keypart_map= keypart_map;
  m_start_key.flag= find_flag;
  DBUG_RETURN(common_index_read(buf, TRUE));
}


/*
  Common routine for a number of index_read variants

  SYNOPSIS
    ha_partition::common_index_read()
      buf             Buffer where the record should be returned
      have_start_key  TRUE <=> the left endpoint is available, i.e. 
                      we're in index_read call or in read_range_first
                      call and the range has left endpoint

                      FALSE <=> there is no left endpoint (we're in
                      read_range_first() call and the range has no left
                      endpoint)
 
  DESCRIPTION
    Start scanning the range (when invoked from read_range_first()) or doing 
    an index lookup (when invoked from index_read_XXX):
     - If possible, perform partition selection
     - Find the set of partitions we're going to use
     - Depending on whether we need ordering:
        NO:  Get the first record from first used partition (see 
             handle_unordered_scan_next_partition)
        YES: Fill the priority queue and get the record that is the first in
             the ordering

  RETURN
    0      OK 
    other  HA_ERR_END_OF_FILE or other error code.
*/

int ha_partition::common_index_read(uchar *buf, bool have_start_key)
{
  int error;
  uint key_len;
  bool reverse_order= FALSE;
  DBUG_ENTER("ha_partition::common_index_read");
  LINT_INIT(key_len); /* used if have_start_key==TRUE */

  DBUG_PRINT("info", ("m_ordered %u m_ordered_scan_ong %u have_start_key %u",
                      m_ordered, m_ordered_scan_ongoing, have_start_key));

  if (have_start_key)
  {
    m_start_key.length= key_len= calculate_key_len(table, active_index, 
                                                   m_start_key.key,
                                                   m_start_key.keypart_map);
    DBUG_ASSERT(key_len);
  }
  if ((error= partition_scan_set_up(buf, have_start_key)))
  {
    DBUG_RETURN(error);
  }

  if (have_start_key && 
      (m_start_key.flag == HA_READ_PREFIX_LAST ||
       m_start_key.flag == HA_READ_PREFIX_LAST_OR_PREV ||
       m_start_key.flag == HA_READ_BEFORE_KEY))
  {
    reverse_order= TRUE;
    m_ordered_scan_ongoing= TRUE;
  }
  DBUG_PRINT("info", ("m_ordered %u m_o_scan_ong %u have_start_key %u",
                      m_ordered, m_ordered_scan_ongoing, have_start_key));
  if (!m_ordered_scan_ongoing ||
      (have_start_key && m_start_key.flag == HA_READ_KEY_EXACT &&
       !m_pkey_is_clustered &&
       key_len >= m_curr_key_info[0]->key_length))
   {
    /*
      We use unordered index scan either when read_range is used and flag
      is set to not use ordered or when an exact key is used and in this
      case all records will be sorted equal and thus the sort order of the
      resulting records doesn't matter.
      We also use an unordered index scan when the number of partitions to
      scan is only one.
      The unordered index scan will use the partition set created.
      Need to set unordered scan ongoing since we can come here even when
      it isn't set.
    */
    DBUG_PRINT("info", ("doing unordered scan"));
    m_ordered_scan_ongoing= FALSE;
    error= handle_unordered_scan_next_partition(buf);
  }
  else
  {
    /*
      In all other cases we will use the ordered index scan. This will use
      the partition set created by the get_partition_set method.
    */
    error= handle_ordered_index_scan(buf, reverse_order);
  }
  DBUG_RETURN(error);
}


/*
  Start an index scan from leftmost record and return first record

  SYNOPSIS
    index_first()
    buf                 Read row in MySQL Row Format

  RETURN VALUE
    >0                  Error code
    0                   Success

  DESCRIPTION
    index_first() asks for the first key in the index.
    This is similar to index_read except that there is no start key since
    the scan starts from the leftmost entry and proceeds forward with
    index_next.

    Called from opt_range.cc, opt_sum.cc, sql_handler.cc,
    and sql_select.cc.
*/

int ha_partition::index_first(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_first");

  end_range= 0;
  m_index_scan_type= partition_index_first;
  DBUG_RETURN(common_first_last(buf));
}


/*
  Start an index scan from rightmost record and return first record
  
  SYNOPSIS
    index_last()
    buf                 Read row in MySQL Row Format

  RETURN VALUE
    >0                  Error code
    0                   Success

  DESCRIPTION
    index_last() asks for the last key in the index.
    This is similar to index_read except that there is no start key since
    the scan starts from the rightmost entry and proceeds forward with
    index_prev.

    Called from opt_range.cc, opt_sum.cc, sql_handler.cc,
    and sql_select.cc.
*/

int ha_partition::index_last(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_last");

  m_index_scan_type= partition_index_last;
  DBUG_RETURN(common_first_last(buf));
}

/*
  Common routine for index_first/index_last

  SYNOPSIS
    ha_partition::common_first_last()
  
  see index_first for rest
*/

int ha_partition::common_first_last(uchar *buf)
{
  int error;

  if ((error= partition_scan_set_up(buf, FALSE)))
    return error;
  if (!m_ordered_scan_ongoing &&
      m_index_scan_type != partition_index_last)
    return handle_unordered_scan_next_partition(buf);
  return handle_ordered_index_scan(buf, FALSE);
}


/*
  Read last using key

  SYNOPSIS
    index_read_last_map()
    buf                   Read row in MySQL Row Format
    key                   Key
    keypart_map           Which part of key is used

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    This is used in join_read_last_key to optimise away an ORDER BY.
    Can only be used on indexes supporting HA_READ_ORDER
*/

int ha_partition::index_read_last_map(uchar *buf, const uchar *key,
                                      key_part_map keypart_map)
{
  DBUG_ENTER("ha_partition::index_read_last");

  m_ordered= TRUE;				// Safety measure
  end_range= 0;
  m_index_scan_type= partition_index_read_last;
  m_start_key.key= key;
  m_start_key.keypart_map= keypart_map;
  m_start_key.flag= HA_READ_PREFIX_LAST;
  DBUG_RETURN(common_index_read(buf, TRUE));
}


/*
  Optimization of the default implementation to take advantage of dynamic
  partition pruning.
*/
int ha_partition::index_read_idx_map(uchar *buf, uint index,
                                     const uchar *key,
                                     key_part_map keypart_map,
                                     enum ha_rkey_function find_flag)
{
  int error= HA_ERR_KEY_NOT_FOUND;
  DBUG_ENTER("ha_partition::index_read_idx_map");

  if (find_flag == HA_READ_KEY_EXACT)
  {
    uint part;
    m_start_key.key= key;
    m_start_key.keypart_map= keypart_map;
    m_start_key.flag= find_flag;
    m_start_key.length= calculate_key_len(table, index, m_start_key.key,
                                          m_start_key.keypart_map);

    get_partition_set(table, buf, index, &m_start_key, &m_part_spec);

    /* 
      We have either found exactly 1 partition
      (in which case start_part == end_part)
      or no matching partitions (start_part > end_part)
    */
    DBUG_ASSERT(m_part_spec.start_part >= m_part_spec.end_part);

    for (part= m_part_spec.start_part; part <= m_part_spec.end_part; part++)
    {
      if (bitmap_is_set(&(m_part_info->used_partitions), part))
      {
        error= m_file[part]->index_read_idx_map(buf, index, key,
                                                keypart_map, find_flag);
        if (error != HA_ERR_KEY_NOT_FOUND &&
            error != HA_ERR_END_OF_FILE)
          break;
      }
    }
    if (part <= m_part_spec.end_part)
      m_last_part= part;
  }
  else
  {
    /*
      If not only used with READ_EXACT, we should investigate if possible
      to optimize for other find_flag's as well.
    */
    DBUG_ASSERT(0);
    /* fall back on the default implementation */
    error= handler::index_read_idx_map(buf, index, key, keypart_map, find_flag);
  }
  DBUG_RETURN(error);
}


/*
  Read next record in a forward index scan

  SYNOPSIS
    index_next()
    buf                   Read row in MySQL Row Format

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    Used to read forward through the index.
*/

int ha_partition::index_next(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_next");

  /*
    TODO(low priority):
    If we want partition to work with the HANDLER commands, we
    must be able to do index_last() -> index_prev() -> index_next()
  */
  DBUG_ASSERT(m_index_scan_type != partition_index_last);
  if (!m_ordered_scan_ongoing)
  {
    DBUG_RETURN(handle_unordered_next(buf, FALSE));
  }
  DBUG_RETURN(handle_ordered_next(buf, FALSE));
}


/*
  Read next record special

  SYNOPSIS
    index_next_same()
    buf                   Read row in MySQL Row Format
    key                   Key
    keylen                Length of key

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    This routine is used to read the next but only if the key is the same
    as supplied in the call.
*/

int ha_partition::index_next_same(uchar *buf, const uchar *key, uint keylen)
{
  DBUG_ENTER("ha_partition::index_next_same");

  DBUG_ASSERT(keylen == m_start_key.length);
  DBUG_ASSERT(m_index_scan_type != partition_index_last);
  if (!m_ordered_scan_ongoing)
    DBUG_RETURN(handle_unordered_next(buf, TRUE));
  DBUG_RETURN(handle_ordered_next(buf, TRUE));
}


/*
  Read next record when performing index scan backwards

  SYNOPSIS
    index_prev()
    buf                   Read row in MySQL Row Format

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    Used to read backwards through the index.
*/

int ha_partition::index_prev(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_prev");

  /* TODO: read comment in index_next */
  DBUG_ASSERT(m_index_scan_type != partition_index_first);
  DBUG_RETURN(handle_ordered_prev(buf));
}


/*
  Start a read of one range with start and end key

  SYNOPSIS
    read_range_first()
    start_key           Specification of start key
    end_key             Specification of end key
    eq_range_arg        Is it equal range
    sorted              Should records be returned in sorted order

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    We reimplement read_range_first since we don't want the compare_key
    check at the end. This is already performed in the partition handler.
    read_range_next is very much different due to that we need to scan
    all underlying handlers.
*/

int ha_partition::read_range_first(const key_range *start_key,
				   const key_range *end_key,
				   bool eq_range_arg, bool sorted)
{
  int error;
  DBUG_ENTER("ha_partition::read_range_first");

  m_ordered= sorted;
  eq_range= eq_range_arg;
  end_range= 0;
  if (end_key)
  {
    end_range= &save_end_range;
    save_end_range= *end_key;
    key_compare_result_on_equal=
      ((end_key->flag == HA_READ_BEFORE_KEY) ? 1 :
       (end_key->flag == HA_READ_AFTER_KEY) ? -1 : 0);
  }

  range_key_part= m_curr_key_info[0]->key_part;
  if (start_key)
    m_start_key= *start_key;
  else
    m_start_key.key= NULL;

  m_index_scan_type= partition_read_range;
  error= common_index_read(m_rec0, test(start_key));
  DBUG_RETURN(error);
}


/*
  Read next record in read of a range with start and end key

  SYNOPSIS
    read_range_next()

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::read_range_next()
{
  DBUG_ENTER("ha_partition::read_range_next");

  if (m_ordered_scan_ongoing)
  {
    DBUG_RETURN(handle_ordered_next(table->record[0], eq_range));
  }
  DBUG_RETURN(handle_unordered_next(table->record[0], eq_range));
}


/*
  Common routine to set up index scans

  SYNOPSIS
    ha_partition::partition_scan_set_up()
      buf            Buffer to later return record in (this function
                     needs it to calculcate partitioning function
                     values)

      idx_read_flag  TRUE <=> m_start_key has range start endpoint which 
                     probably can be used to determine the set of partitions
                     to scan.
                     FALSE <=> there is no start endpoint.

  DESCRIPTION
    Find out which partitions we'll need to read when scanning the specified
    range.

    If we need to scan only one partition, set m_ordered_scan_ongoing=FALSE
    as we will not need to do merge ordering.

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::partition_scan_set_up(uchar * buf, bool idx_read_flag)
{
  DBUG_ENTER("ha_partition::partition_scan_set_up");

  if (idx_read_flag)
    get_partition_set(table,buf,active_index,&m_start_key,&m_part_spec);
  else
  {
    m_part_spec.start_part= 0;
    m_part_spec.end_part= m_tot_parts - 1;
  }
  if (m_part_spec.start_part > m_part_spec.end_part)
  {
    /*
      We discovered a partition set but the set was empty so we report
      key not found.
    */
    DBUG_PRINT("info", ("scan with no partition to scan"));
    table->status= STATUS_NOT_FOUND;
    DBUG_RETURN(HA_ERR_END_OF_FILE);
  }
  if (m_part_spec.start_part == m_part_spec.end_part)
  {
    /*
      We discovered a single partition to scan, this never needs to be
      performed using the ordered index scan.
    */
    DBUG_PRINT("info", ("index scan using the single partition %d",
			m_part_spec.start_part));
    m_ordered_scan_ongoing= FALSE;
  }
  else
  {
    /*
      Set m_ordered_scan_ongoing according how the scan should be done
      Only exact partitions are discovered atm by get_partition_set.
      Verify this, also bitmap must have at least one bit set otherwise
      the result from this table is the empty set.
    */
    uint start_part= bitmap_get_first_set(&(m_part_info->used_partitions));
    if (start_part == MY_BIT_NONE)
    {
      DBUG_PRINT("info", ("scan with no partition to scan"));
      table->status= STATUS_NOT_FOUND;
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
    if (start_part > m_part_spec.start_part)
      m_part_spec.start_part= start_part;
    DBUG_ASSERT(m_part_spec.start_part < m_tot_parts);
    m_ordered_scan_ongoing= m_ordered;
  }
  DBUG_ASSERT(m_part_spec.start_part < m_tot_parts &&
              m_part_spec.end_part < m_tot_parts);
  DBUG_RETURN(0);
}


/****************************************************************************
  Unordered Index Scan Routines
****************************************************************************/
/*
  Common routine to handle index_next with unordered results

  SYNOPSIS
    handle_unordered_next()
    out:buf                       Read row in MySQL Row Format
    next_same                     Called from index_next_same

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code

  DESCRIPTION
    These routines are used to scan partitions without considering order.
    This is performed in two situations.
    1) In read_multi_range this is the normal case
    2) When performing any type of index_read, index_first, index_last where
    all fields in the partition function is bound. In this case the index
    scan is performed on only one partition and thus it isn't necessary to
    perform any sort.
*/

int ha_partition::handle_unordered_next(uchar *buf, bool is_next_same)
{
  handler *file= m_file[m_part_spec.start_part];
  int error;
  DBUG_ENTER("ha_partition::handle_unordered_next");

  /*
    We should consider if this should be split into three functions as
    partition_read_range is_next_same are always local constants
  */

  if (m_index_scan_type == partition_read_range)
  {
    if (!(error= file->read_range_next()))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);
    }
  }
  else if (is_next_same)
  {
    if (!(error= file->index_next_same(buf, m_start_key.key,
                                       m_start_key.length)))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);
    }
  }
  else 
  {
    if (!(error= file->index_next(buf)))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);                           // Row was in range
    }
  }

  if (error == HA_ERR_END_OF_FILE)
  {
    m_part_spec.start_part++;                    // Start using next part
    error= handle_unordered_scan_next_partition(buf);
  }
  DBUG_RETURN(error);
}


/*
  Handle index_next when changing to new partition

  SYNOPSIS
    handle_unordered_scan_next_partition()
    buf                       Read row in MySQL Row Format

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code

  DESCRIPTION
    This routine is used to start the index scan on the next partition.
    Both initial start and after completing scan on one partition.
*/

int ha_partition::handle_unordered_scan_next_partition(uchar * buf)
{
  uint i;
  DBUG_ENTER("ha_partition::handle_unordered_scan_next_partition");

  for (i= m_part_spec.start_part; i <= m_part_spec.end_part; i++)
  {
    int error;
    handler *file;

    if (!(bitmap_is_set(&(m_part_info->used_partitions), i)))
      continue;
    file= m_file[i];
    m_part_spec.start_part= i;
    switch (m_index_scan_type) {
    case partition_read_range:
      DBUG_PRINT("info", ("read_range_first on partition %d", i));
      error= file->read_range_first(m_start_key.key? &m_start_key: NULL,
                                    end_range, eq_range, FALSE);
      break;
    case partition_index_read:
      DBUG_PRINT("info", ("index_read on partition %d", i));
      error= file->index_read_map(buf, m_start_key.key,
                                  m_start_key.keypart_map,
                                  m_start_key.flag);
      break;
    case partition_index_first:
      DBUG_PRINT("info", ("index_first on partition %d", i));
      error= file->index_first(buf);
      break;
    case partition_index_first_unordered:
      /*
        We perform a scan without sorting and this means that we
        should not use the index_first since not all handlers
        support it and it is also unnecessary to restrict sort
        order.
      */
      DBUG_PRINT("info", ("read_range_first on partition %d", i));
      table->record[0]= buf;
      error= file->read_range_first(0, end_range, eq_range, 0);
      table->record[0]= m_rec0;
      break;
    default:
      DBUG_ASSERT(FALSE);
      DBUG_RETURN(1);
    }
    if (!error)
    {
      m_last_part= i;
      DBUG_RETURN(0);
    }
    if ((error != HA_ERR_END_OF_FILE) && (error != HA_ERR_KEY_NOT_FOUND))
      DBUG_RETURN(error);
    DBUG_PRINT("info", ("HA_ERR_END_OF_FILE on partition %d", i));
  }
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(HA_ERR_END_OF_FILE);
}


/*
  Common routine to start index scan with ordered results

  SYNOPSIS
    handle_ordered_index_scan()
    out:buf                       Read row in MySQL Row Format

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code

  DESCRIPTION
    This part contains the logic to handle index scans that require ordered
    output. This includes all except those started by read_range_first with
    the flag ordered set to FALSE. Thus most direct index_read and all
    index_first and index_last.

    We implement ordering by keeping one record plus a key buffer for each
    partition. Every time a new entry is requested we will fetch a new
    entry from the partition that is currently not filled with an entry.
    Then the entry is put into its proper sort position.

    Returning a record is done by getting the top record, copying the
    record to the request buffer and setting the partition as empty on
    entries.
*/

int ha_partition::handle_ordered_index_scan(uchar *buf, bool reverse_order)
{
  uint i;
  uint j= 0;
  bool found= FALSE;
  DBUG_ENTER("ha_partition::handle_ordered_index_scan");

  m_top_entry= NO_CURRENT_PART_ID;
  queue_remove_all(&m_queue);

  DBUG_PRINT("info", ("m_part_spec.start_part %d", m_part_spec.start_part));
  for (i= m_part_spec.start_part; i <= m_part_spec.end_part; i++)
  {
    if (!(bitmap_is_set(&(m_part_info->used_partitions), i)))
      continue;
    uchar *rec_buf_ptr= rec_buf(i);
    int error;
    handler *file= m_file[i];

    switch (m_index_scan_type) {
    case partition_index_read:
      error= file->index_read_map(rec_buf_ptr,
                                  m_start_key.key,
                                  m_start_key.keypart_map,
                                  m_start_key.flag);
      break;
    case partition_index_first:
      error= file->index_first(rec_buf_ptr);
      reverse_order= FALSE;
      break;
    case partition_index_last:
      error= file->index_last(rec_buf_ptr);
      reverse_order= TRUE;
      break;
    case partition_index_read_last:
      error= file->index_read_last_map(rec_buf_ptr,
                                       m_start_key.key,
                                       m_start_key.keypart_map);
      reverse_order= TRUE;
      break;
    case partition_read_range:
    {
      /* 
        This can only read record to table->record[0], as it was set when
        the table was being opened. We have to memcpy data ourselves.
      */
      error= file->read_range_first(m_start_key.key? &m_start_key: NULL,
                                    end_range, eq_range, TRUE);
      memcpy(rec_buf_ptr, table->record[0], m_rec_length);
      reverse_order= FALSE;
      break;
    }
    default:
      DBUG_ASSERT(FALSE);
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
    if (!error)
    {
      found= TRUE;
      /*
        Initialize queue without order first, simply insert
      */
      queue_element(&m_queue, j++)= (uchar*)queue_buf(i);
    }
    else if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
    {
      DBUG_RETURN(error);
    }
  }
  if (found)
  {
    /*
      We found at least one partition with data, now sort all entries and
      after that read the first entry and copy it to the buffer to return in.
    */
    queue_set_max_at_top(&m_queue, reverse_order);
    queue_set_cmp_arg(&m_queue, (void*)m_curr_key_info);
    m_queue.elements= j;
    queue_fix(&m_queue);
    return_top_record(buf);
    table->status= 0;
    DBUG_PRINT("info", ("Record returned from partition %d", m_top_entry));
    DBUG_RETURN(0);
  }
  DBUG_RETURN(HA_ERR_END_OF_FILE);
}


/*
  Return the top record in sort order

  SYNOPSIS
    return_top_record()
    out:buf                  Row returned in MySQL Row Format

  RETURN VALUE
    NONE
*/

void ha_partition::return_top_record(uchar *buf)
{
  uint part_id;
  uchar *key_buffer= queue_top(&m_queue);
  uchar *rec_buffer= key_buffer + PARTITION_BYTES_IN_POS;

  part_id= uint2korr(key_buffer);
  memcpy(buf, rec_buffer, m_rec_length);
  m_last_part= part_id;
  m_top_entry= part_id;
}


/*
  Common routine to handle index_next with ordered results

  SYNOPSIS
    handle_ordered_next()
    out:buf                       Read row in MySQL Row Format
    next_same                     Called from index_next_same

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code
*/

int ha_partition::handle_ordered_next(uchar *buf, bool is_next_same)
{
  int error;
  uint part_id= m_top_entry;
  handler *file= m_file[part_id];
  DBUG_ENTER("ha_partition::handle_ordered_next");
  
  if (m_index_scan_type == partition_read_range)
  {
    error= file->read_range_next();
    memcpy(rec_buf(part_id), table->record[0], m_rec_length);
  }
  else if (!is_next_same)
    error= file->index_next(rec_buf(part_id));
  else
    error= file->index_next_same(rec_buf(part_id), m_start_key.key,
				 m_start_key.length);
  if (error)
  {
    if (error == HA_ERR_END_OF_FILE)
    {
      /* Return next buffered row */
      queue_remove(&m_queue, (uint) 0);
      if (m_queue.elements)
      {
         DBUG_PRINT("info", ("Record returned from partition %u (2)",
                     m_top_entry));
         return_top_record(buf);
         table->status= 0;
         error= 0;
      }
    }
    DBUG_RETURN(error);
  }
  queue_replaced(&m_queue);
  return_top_record(buf);
  DBUG_PRINT("info", ("Record returned from partition %u", m_top_entry));
  DBUG_RETURN(0);
}


/*
  Common routine to handle index_prev with ordered results

  SYNOPSIS
    handle_ordered_prev()
    out:buf                       Read row in MySQL Row Format

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code
*/

int ha_partition::handle_ordered_prev(uchar *buf)
{
  int error;
  uint part_id= m_top_entry;
  handler *file= m_file[part_id];
  DBUG_ENTER("ha_partition::handle_ordered_prev");

  if ((error= file->index_prev(rec_buf(part_id))))
  {
    if (error == HA_ERR_END_OF_FILE)
    {
      queue_remove(&m_queue, (uint) 0);
      if (m_queue.elements)
      {
	return_top_record(buf);
	DBUG_PRINT("info", ("Record returned from partition %d (2)",
			    m_top_entry));
        error= 0;
        table->status= 0;
      }
    }
    DBUG_RETURN(error);
  }
  queue_replaced(&m_queue);
  return_top_record(buf);
  DBUG_PRINT("info", ("Record returned from partition %d", m_top_entry));
  DBUG_RETURN(0);
}


/****************************************************************************
                MODULE information calls
****************************************************************************/

/*
  These are all first approximations of the extra, info, scan_time
  and read_time calls
*/

/*
  General method to gather info from handler

  SYNOPSIS
    info()
    flag              Specifies what info is requested

  RETURN VALUE
    NONE

  DESCRIPTION
    ::info() is used to return information to the optimizer.
    Currently this table handler doesn't implement most of the fields
    really needed. SHOW also makes use of this data
    Another note, if your handler doesn't proved exact record count,
    you will probably want to have the following in your code:
    if (records < 2)
      records = 2;
    The reason is that the server will optimize for cases of only a single
    record. If in a table scan you don't know the number of records
    it will probably be better to set records to two so you can return
    as many records as you need.

    Along with records a few more variables you may wish to set are:
      records
      deleted
      data_file_length
      index_file_length
      delete_length
      check_time
    Take a look at the public variables in handler.h for more information.

    Called in:
      filesort.cc
      ha_heap.cc
      item_sum.cc
      opt_sum.cc
      sql_delete.cc
     sql_delete.cc
     sql_derived.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_show.cc
      sql_show.cc
      sql_show.cc
      sql_show.cc
      sql_table.cc
      sql_union.cc
      sql_update.cc

    Some flags that are not implemented
      HA_STATUS_POS:
        This parameter is never used from the MySQL Server. It is checked in a
        place in MyISAM so could potentially be used by MyISAM specific
        programs.
      HA_STATUS_NO_LOCK:
      This is declared and often used. It's only used by MyISAM.
      It means that MySQL doesn't need the absolute latest statistics
      information. This may save the handler from doing internal locks while
      retrieving statistics data.
*/

int ha_partition::info(uint flag)
{
  DBUG_ENTER("ha_partition::info");

  if (flag & HA_STATUS_AUTO)
  {
    bool auto_inc_is_first_in_idx= (table_share->next_number_keypart == 0);
    HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
    DBUG_PRINT("info", ("HA_STATUS_AUTO"));
    if (!table->found_next_number_field)
      stats.auto_increment_value= 0;
    else if (ha_data->auto_inc_initialized)
    {
      lock_auto_increment();
      stats.auto_increment_value= ha_data->next_auto_inc_val;
      unlock_auto_increment();
    }
    else
    {
      lock_auto_increment();
      /* to avoid two concurrent initializations, check again when locked */
      if (ha_data->auto_inc_initialized)
        stats.auto_increment_value= ha_data->next_auto_inc_val;
      else
      {
        handler *file, **file_array;
        ulonglong auto_increment_value= 0;
        file_array= m_file;
        DBUG_PRINT("info",
                   ("checking all partitions for auto_increment_value"));
        do
        {
          file= *file_array;
          file->info(HA_STATUS_AUTO);
          set_if_bigger(auto_increment_value,
                        file->stats.auto_increment_value);
        } while (*(++file_array));

        DBUG_ASSERT(auto_increment_value);
        stats.auto_increment_value= auto_increment_value;
        if (auto_inc_is_first_in_idx)
        {
          set_if_bigger(ha_data->next_auto_inc_val, auto_increment_value);
          ha_data->auto_inc_initialized= TRUE;
          DBUG_PRINT("info", ("initializing next_auto_inc_val to %lu",
                              (ulong) ha_data->next_auto_inc_val));
        }
      }
      unlock_auto_increment();
    }
  }
  if (flag & HA_STATUS_VARIABLE)
  {
    DBUG_PRINT("info", ("HA_STATUS_VARIABLE"));
    /*
      Calculates statistical variables
      records:           Estimate of number records in table
      We report sum (always at least 2 if not empty)
      deleted:           Estimate of number holes in the table due to
      deletes
      We report sum
      data_file_length:  Length of data file, in principle bytes in table
      We report sum
      index_file_length: Length of index file, in principle bytes in
      indexes in the table
      We report sum
      delete_length: Length of free space easily used by new records in table
      We report sum
      mean_record_length:Mean record length in the table
      We calculate this
      check_time:        Time of last check (only applicable to MyISAM)
      We report last time of all underlying handlers
    */
    handler *file, **file_array;
    stats.records= 0;
    stats.deleted= 0;
    stats.data_file_length= 0;
    stats.index_file_length= 0;
    stats.check_time= 0;
    stats.delete_length= 0;
    file_array= m_file;
    do
    {
      if (bitmap_is_set(&(m_part_info->used_partitions), (file_array - m_file)))
      {
        file= *file_array;
        file->info(HA_STATUS_VARIABLE);
        stats.records+= file->stats.records;
        stats.deleted+= file->stats.deleted;
        stats.data_file_length+= file->stats.data_file_length;
        stats.index_file_length+= file->stats.index_file_length;
        stats.delete_length+= file->stats.delete_length;
        if (file->stats.check_time > stats.check_time)
          stats.check_time= file->stats.check_time;
      }
    } while (*(++file_array));
    if (stats.records && stats.records < 2 &&
        !(m_file[0]->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))
      stats.records= 2;
    if (stats.records > 0)
      stats.mean_rec_length= (ulong) (stats.data_file_length / stats.records);
    else
      stats.mean_rec_length= 0;
  }
  if (flag & HA_STATUS_CONST)
  {
    DBUG_PRINT("info", ("HA_STATUS_CONST"));
    /*
      Recalculate loads of constant variables. MyISAM also sets things
      directly on the table share object.

      Check whether this should be fixed since handlers should not
      change things directly on the table object.

      Monty comment: This should NOT be changed!  It's the handlers
      responsibility to correct table->s->keys_xxxx information if keys
      have been disabled.

      The most important parameters set here is records per key on
      all indexes. block_size and primar key ref_length.

      For each index there is an array of rec_per_key.
      As an example if we have an index with three attributes a,b and c
      we will have an array of 3 rec_per_key.
      rec_per_key[0] is an estimate of number of records divided by
      number of unique values of the field a.
      rec_per_key[1] is an estimate of the number of records divided
      by the number of unique combinations of the fields a and b.
      rec_per_key[2] is an estimate of the number of records divided
      by the number of unique combinations of the fields a,b and c.

      Many handlers only set the value of rec_per_key when all fields
      are bound (rec_per_key[2] in the example above).

      If the handler doesn't support statistics, it should set all of the
      above to 0.

      We first scans through all partitions to get the one holding most rows.
      We will then allow the handler with the most rows to set
      the rec_per_key and use this as an estimate on the total table.

      max_data_file_length:     Maximum data file length
      We ignore it, is only used in
      SHOW TABLE STATUS
      max_index_file_length:    Maximum index file length
      We ignore it since it is never used
      block_size:               Block size used
      We set it to the value of the first handler
      ref_length:               We set this to the value calculated
      and stored in local object
      create_time:              Creation time of table

      So we calculate these constants by using the variables from the
      handler with most rows.
    */
    handler *file, **file_array;
    ulonglong max_records= 0;
    uint32 i= 0;
    uint32 handler_instance= 0;

    file_array= m_file;
    do
    {
      file= *file_array;
      /* Get variables if not already done */
      if (!(flag & HA_STATUS_VARIABLE) ||
          !bitmap_is_set(&(m_part_info->used_partitions),
                         (file_array - m_file)))
        file->info(HA_STATUS_VARIABLE);
      if (file->stats.records > max_records)
      {
        max_records= file->stats.records;
        handler_instance= i;
      }
      i++;
    } while (*(++file_array));

    file= m_file[handler_instance];
    file->info(HA_STATUS_CONST);
    stats.block_size= file->stats.block_size;
    stats.create_time= file->stats.create_time;
    ref_length= m_ref_length;
  }
  if (flag & HA_STATUS_ERRKEY)
  {
    handler *file= m_file[m_last_part];
    DBUG_PRINT("info", ("info: HA_STATUS_ERRKEY"));
    /*
      This flag is used to get index number of the unique index that
      reported duplicate key
      We will report the errkey on the last handler used and ignore the rest
      Note: all engines does not support HA_STATUS_ERRKEY, so set errkey.
    */
    file->errkey= errkey;
    file->info(HA_STATUS_ERRKEY);
    errkey= file->errkey;
  }
  if (flag & HA_STATUS_TIME)
  {
    handler *file, **file_array;
    DBUG_PRINT("info", ("info: HA_STATUS_TIME"));
    /*
      This flag is used to set the latest update time of the table.
      Used by SHOW commands
      We will report the maximum of these times
    */
    stats.update_time= 0;
    file_array= m_file;
    do
    {
      file= *file_array;
      file->info(HA_STATUS_TIME);
      if (file->stats.update_time > stats.update_time)
	stats.update_time= file->stats.update_time;
    } while (*(++file_array));
  }
  DBUG_RETURN(0);
}


void ha_partition::get_dynamic_partition_info(PARTITION_INFO *stat_info,
                                              uint part_id)
{
  handler *file= m_file[part_id];
  file->info(HA_STATUS_CONST | HA_STATUS_TIME | HA_STATUS_VARIABLE |
             HA_STATUS_NO_LOCK);

  stat_info->records=              file->stats.records;
  stat_info->mean_rec_length=      file->stats.mean_rec_length;
  stat_info->data_file_length=     file->stats.data_file_length;
  stat_info->max_data_file_length= file->stats.max_data_file_length;
  stat_info->index_file_length=    file->stats.index_file_length;
  stat_info->delete_length=        file->stats.delete_length;
  stat_info->create_time=          file->stats.create_time;
  stat_info->update_time=          file->stats.update_time;
  stat_info->check_time=           file->stats.check_time;
  stat_info->check_sum= 0;
  if (file->ha_table_flags() & (HA_HAS_OLD_CHECKSUM | HA_HAS_NEW_CHECKSUM))
    stat_info->check_sum= file->checksum();
  return;
}


/*
  General function to prepare handler for certain behavior

  SYNOPSIS
    extra()
    operation              Operation type for extra call

  RETURN VALUE
    >0                     Error code
    0                      Success

  DESCRIPTION
  extra() is called whenever the server wishes to send a hint to
  the storage engine. The MyISAM engine implements the most hints.

  We divide the parameters into the following categories:
  1) Parameters used by most handlers
  2) Parameters used by some non-MyISAM handlers
  3) Parameters used only by MyISAM
  4) Parameters only used by temporary tables for query processing
  5) Parameters only used by MyISAM internally
  6) Parameters not used at all
  7) Parameters only used by federated tables for query processing
  8) Parameters only used by NDB

  The partition handler need to handle category 1), 2) and 3).

  1) Parameters used by most handlers
  -----------------------------------
  HA_EXTRA_RESET:
    This option is used by most handlers and it resets the handler state
    to the same state as after an open call. This includes releasing
    any READ CACHE or WRITE CACHE or other internal buffer used.

    It is called from the reset method in the handler interface. There are
    three instances where this is called.
    1) After completing a INSERT ... SELECT ... query the handler for the
       table inserted into is reset
    2) It is called from close_thread_table which in turn is called from
       close_thread_tables except in the case where the tables are locked
       in which case ha_commit_stmt is called instead.
       It is only called from here if refresh_version hasn't changed and the
       table is not an old table when calling close_thread_table.
       close_thread_tables is called from many places as a general clean up
       function after completing a query.
    3) It is called when deleting the QUICK_RANGE_SELECT object if the
       QUICK_RANGE_SELECT object had its own handler object. It is called
       immediatley before close of this local handler object.
  HA_EXTRA_KEYREAD:
  HA_EXTRA_NO_KEYREAD:
    These parameters are used to provide an optimisation hint to the handler.
    If HA_EXTRA_KEYREAD is set it is enough to read the index fields, for
    many handlers this means that the index-only scans can be used and it
    is not necessary to use the real records to satisfy this part of the
    query. Index-only scans is a very important optimisation for disk-based
    indexes. For main-memory indexes most indexes contain a reference to the
    record and thus KEYREAD only says that it is enough to read key fields.
    HA_EXTRA_NO_KEYREAD disables this for the handler, also HA_EXTRA_RESET
    will disable this option.
    The handler will set HA_KEYREAD_ONLY in its table flags to indicate this
    feature is supported.
  HA_EXTRA_FLUSH:
    Indication to flush tables to disk, is supposed to be used to
    ensure disk based tables are flushed at end of query execution.
    Currently is never used.

  2) Parameters used by some non-MyISAM handlers
  ----------------------------------------------
  HA_EXTRA_KEYREAD_PRESERVE_FIELDS:
    This is a strictly InnoDB feature that is more or less undocumented.
    When it is activated InnoDB copies field by field from its fetch
    cache instead of all fields in one memcpy. Have no idea what the
    purpose of this is.
    Cut from include/my_base.h:
    When using HA_EXTRA_KEYREAD, overwrite only key member fields and keep
    other fields intact. When this is off (by default) InnoDB will use memcpy
    to overwrite entire row.
  HA_EXTRA_IGNORE_DUP_KEY:
  HA_EXTRA_NO_IGNORE_DUP_KEY:
    Informs the handler to we will not stop the transaction if we get an
    duplicate key errors during insert/upate.
    Always called in pair, triggered by INSERT IGNORE and other similar
    SQL constructs.
    Not used by MyISAM.

  3) Parameters used only by MyISAM
  ---------------------------------
  HA_EXTRA_NORMAL:
    Only used in MyISAM to reset quick mode, not implemented by any other
    handler. Quick mode is also reset in MyISAM by HA_EXTRA_RESET.

    It is called after completing a successful DELETE query if the QUICK
    option is set.

  HA_EXTRA_QUICK:
    When the user does DELETE QUICK FROM table where-clause; this extra
    option is called before the delete query is performed and
    HA_EXTRA_NORMAL is called after the delete query is completed.
    Temporary tables used internally in MySQL always set this option

    The meaning of quick mode is that when deleting in a B-tree no merging
    of leafs is performed. This is a common method and many large DBMS's
    actually only support this quick mode since it is very difficult to
    merge leaves in a tree used by many threads concurrently.

  HA_EXTRA_CACHE:
    This flag is usually set with extra_opt along with a cache size.
    The size of this buffer is set by the user variable
    record_buffer_size. The value of this cache size is the amount of
    data read from disk in each fetch when performing a table scan.
    This means that before scanning a table it is normal to call
    extra with HA_EXTRA_CACHE and when the scan is completed to call
    HA_EXTRA_NO_CACHE to release the cache memory.

    Some special care is taken when using this extra parameter since there
    could be a write ongoing on the table in the same statement. In this
    one has to take special care since there might be a WRITE CACHE as
    well. HA_EXTRA_CACHE specifies using a READ CACHE and using
    READ CACHE and WRITE CACHE at the same time is not possible.

    Only MyISAM currently use this option.

    It is set when doing full table scans using rr_sequential and
    reset when completing such a scan with end_read_record
    (resetting means calling extra with HA_EXTRA_NO_CACHE).

    It is set in filesort.cc for MyISAM internal tables and it is set in
    a multi-update where HA_EXTRA_CACHE is called on a temporary result
    table and after that ha_rnd_init(0) on table to be updated
    and immediately after that HA_EXTRA_NO_CACHE on table to be updated.

    Apart from that it is always used from init_read_record but not when
    used from UPDATE statements. It is not used from DELETE statements
    with ORDER BY and LIMIT but it is used in normal scan loop in DELETE
    statements. The reason here is that DELETE's in MyISAM doesn't move
    existings data rows.

    It is also set in copy_data_between_tables when scanning the old table
    to copy over to the new table.
    And it is set in join_init_read_record where quick objects are used
    to perform a scan on the table. In this case the full table scan can
    even be performed multiple times as part of the nested loop join.

    For purposes of the partition handler it is obviously necessary to have
    special treatment of this extra call. If we would simply pass this
    extra call down to each handler we would allocate
    cache size * no of partitions amount of memory and this is not
    necessary since we will only scan one partition at a time when doing
    full table scans.

    Thus we treat it by first checking whether we have MyISAM handlers in
    the table, if not we simply ignore the call and if we have we will
    record the call but will not call any underlying handler yet. Then
    when performing the sequential scan we will check this recorded value
    and call extra_opt whenever we start scanning a new partition.

  HA_EXTRA_NO_CACHE:
    When performing a UNION SELECT HA_EXTRA_NO_CACHE is called from the
    flush method in the select_union class.
    It is used to some extent when insert delayed inserts.
    See HA_EXTRA_RESET_STATE for use in conjunction with delete_all_rows().

    It should be ok to call HA_EXTRA_NO_CACHE on all underlying handlers
    if they are MyISAM handlers. Other handlers we can ignore the call
    for. If no cache is in use they will quickly return after finding
    this out. And we also ensure that all caches are disabled and no one
    is left by mistake.
    In the future this call will probably be deleted and we will instead call
    ::reset();

  HA_EXTRA_WRITE_CACHE:
    See above, called from various places. It is mostly used when we
    do INSERT ... SELECT
    No special handling to save cache space is developed currently.

  HA_EXTRA_PREPARE_FOR_UPDATE:
    This is called as part of a multi-table update. When the table to be
    updated is also scanned then this informs MyISAM handler to drop any
    caches if dynamic records are used (fixed size records do not care
    about this call). We pass this along to the first partition to scan, and
    flag that it is to be called after HA_EXTRA_CACHE when moving to the next
    partition to scan.

  HA_EXTRA_PREPARE_FOR_DROP:
    Only used by MyISAM, called in preparation for a DROP TABLE.
    It's used mostly by Windows that cannot handle dropping an open file.
    On other platforms it has the same effect as HA_EXTRA_FORCE_REOPEN.

  HA_EXTRA_PREPARE_FOR_RENAME:
    Informs the handler we are about to attempt a rename of the table.

  HA_EXTRA_READCHECK:
  HA_EXTRA_NO_READCHECK:
    Only one call to HA_EXTRA_NO_READCHECK from ha_open where it says that
    this is not needed in SQL. The reason for this call is that MyISAM sets
    the READ_CHECK_USED in the open call so the call is needed for MyISAM
    to reset this feature.
    The idea with this parameter was to inform of doing/not doing a read
    check before applying an update. Since SQL always performs a read before
    applying the update No Read Check is needed in MyISAM as well.

    This is a cut from Docs/myisam.txt
     Sometimes you might want to force an update without checking whether
     another user has changed the record since you last read it. This is
     somewhat dangerous, so it should ideally not be used. That can be
     accomplished by wrapping the mi_update() call in two calls to mi_extra(),
     using these functions:
     HA_EXTRA_NO_READCHECK=5                 No readcheck on update
     HA_EXTRA_READCHECK=6                    Use readcheck (def)

  HA_EXTRA_FORCE_REOPEN:
    Only used by MyISAM, called when altering table, closing tables to
    enforce a reopen of the table files.

  4) Parameters only used by temporary tables for query processing
  ----------------------------------------------------------------
  HA_EXTRA_RESET_STATE:
    Same as reset() except that buffers are not released. If there is
    a READ CACHE it is reinit'ed. A cache is reinit'ed to restart reading
    or to change type of cache between READ CACHE and WRITE CACHE.

    This extra function is always called immediately before calling
    delete_all_rows on the handler for temporary tables.
    There are cases however when HA_EXTRA_RESET_STATE isn't called in
    a similar case for a temporary table in sql_union.cc and in two other
    cases HA_EXTRA_NO_CACHE is called before and HA_EXTRA_WRITE_CACHE
    called afterwards.
    The case with HA_EXTRA_NO_CACHE and HA_EXTRA_WRITE_CACHE means
    disable caching, delete all rows and enable WRITE CACHE. This is
    used for temporary tables containing distinct sums and a
    functional group.

    The only case that delete_all_rows is called on non-temporary tables
    is in sql_delete.cc when DELETE FROM table; is called by a user.
    In this case no special extra calls are performed before or after this
    call.

    The partition handler should not need to bother about this one. It
    should never be called.

  HA_EXTRA_NO_ROWS:
    Don't insert rows indication to HEAP and MyISAM, only used by temporary
    tables used in query processing.
    Not handled by partition handler.

  5) Parameters only used by MyISAM internally
  --------------------------------------------
  HA_EXTRA_REINIT_CACHE:
    This call reinitializes the READ CACHE described above if there is one
    and otherwise the call is ignored.

    We can thus safely call it on all underlying handlers if they are
    MyISAM handlers. It is however never called so we don't handle it at all.
  HA_EXTRA_FLUSH_CACHE:
    Flush WRITE CACHE in MyISAM. It is only from one place in the code.
    This is in sql_insert.cc where it is called if the table_flags doesn't
    contain HA_DUPLICATE_POS. The only handler having the HA_DUPLICATE_POS
    set is the MyISAM handler and so the only handler not receiving this
    call is MyISAM.
    Thus in effect this call is called but never used. Could be removed
    from sql_insert.cc
  HA_EXTRA_NO_USER_CHANGE:
    Only used by MyISAM, never called.
    Simulates lock_type as locked.
  HA_EXTRA_WAIT_LOCK:
  HA_EXTRA_WAIT_NOLOCK:
    Only used by MyISAM, called from MyISAM handler but never from server
    code on top of the handler.
    Sets lock_wait on/off
  HA_EXTRA_NO_KEYS:
    Only used MyISAM, only used internally in MyISAM handler, never called
    from server level.
  HA_EXTRA_KEYREAD_CHANGE_POS:
  HA_EXTRA_REMEMBER_POS:
  HA_EXTRA_RESTORE_POS:
  HA_EXTRA_PRELOAD_BUFFER_SIZE:
  HA_EXTRA_CHANGE_KEY_TO_DUP:
  HA_EXTRA_CHANGE_KEY_TO_UNIQUE:
    Only used by MyISAM, never called.

  6) Parameters not used at all
  -----------------------------
  HA_EXTRA_KEY_CACHE:
  HA_EXTRA_NO_KEY_CACHE:
    This parameters are no longer used and could be removed.

  7) Parameters only used by federated tables for query processing
  ----------------------------------------------------------------
  HA_EXTRA_INSERT_WITH_UPDATE:
    Inform handler that an "INSERT...ON DUPLICATE KEY UPDATE" will be
    executed. This condition is unset by HA_EXTRA_NO_IGNORE_DUP_KEY.

  8) Parameters only used by NDB
  ------------------------------
  HA_EXTRA_DELETE_CANNOT_BATCH:
  HA_EXTRA_UPDATE_CANNOT_BATCH:
    Inform handler that delete_row()/update_row() cannot batch deletes/updates
    and should perform them immediately. This may be needed when table has 
    AFTER DELETE/UPDATE triggers which access to subject table.
    These flags are reset by the handler::extra(HA_EXTRA_RESET) call.
*/

int ha_partition::extra(enum ha_extra_function operation)
{
  DBUG_ENTER("ha_partition:extra");
  DBUG_PRINT("info", ("operation: %d", (int) operation));

  switch (operation) {
    /* Category 1), used by most handlers */
  case HA_EXTRA_KEYREAD:
  case HA_EXTRA_NO_KEYREAD:
  case HA_EXTRA_FLUSH:
  case HA_EXTRA_PREPARE_FOR_FORCED_CLOSE:
    DBUG_RETURN(loop_extra(operation));

    /* Category 2), used by non-MyISAM handlers */
  case HA_EXTRA_IGNORE_DUP_KEY:
  case HA_EXTRA_NO_IGNORE_DUP_KEY:
  case HA_EXTRA_KEYREAD_PRESERVE_FIELDS:
  {
    if (!m_myisam)
      DBUG_RETURN(loop_extra(operation));
    break;
  }

  /* Category 3), used by MyISAM handlers */
  case HA_EXTRA_PREPARE_FOR_RENAME:
    DBUG_RETURN(prepare_for_rename());
    break;
  case HA_EXTRA_PREPARE_FOR_UPDATE:
    /*
      Needs to be run on the first partition in the range now, and 
      later in late_extra_cache, when switching to a new partition to scan.
    */
    m_extra_prepare_for_update= TRUE;
    if (m_part_spec.start_part != NO_CURRENT_PART_ID)
    {
      if (!m_extra_cache)
        m_extra_cache_part_id= m_part_spec.start_part;
      DBUG_ASSERT(m_extra_cache_part_id == m_part_spec.start_part);
      VOID(m_file[m_part_spec.start_part]->extra(HA_EXTRA_PREPARE_FOR_UPDATE));
    }
    break;
  case HA_EXTRA_NORMAL:
  case HA_EXTRA_QUICK:
  case HA_EXTRA_FORCE_REOPEN:
  case HA_EXTRA_PREPARE_FOR_DROP:
  case HA_EXTRA_FLUSH_CACHE:
  {
    DBUG_RETURN(loop_extra(operation));
  }
  case HA_EXTRA_NO_READCHECK:
  {
    /*
      This is only done as a part of ha_open, which is also used in
      ha_partition::open, so no need to do anything.
    */
    break;
  }
  case HA_EXTRA_CACHE:
  {
    prepare_extra_cache(0);
    break;
  }
  case HA_EXTRA_NO_CACHE:
  {
    int ret= 0;
    if (m_extra_cache_part_id != NO_CURRENT_PART_ID)
      ret= m_file[m_extra_cache_part_id]->extra(HA_EXTRA_NO_CACHE);
    m_extra_cache= FALSE;
    m_extra_cache_size= 0;
    m_extra_prepare_for_update= FALSE;
    m_extra_cache_part_id= NO_CURRENT_PART_ID;
    DBUG_RETURN(ret);
  }
  case HA_EXTRA_WRITE_CACHE:
  {
    m_extra_cache= FALSE;
    m_extra_cache_size= 0;
    m_extra_prepare_for_update= FALSE;
    m_extra_cache_part_id= NO_CURRENT_PART_ID;
    DBUG_RETURN(loop_extra(operation));
  }
  case HA_EXTRA_IGNORE_NO_KEY:
  case HA_EXTRA_NO_IGNORE_NO_KEY:
  {
    /*
      Ignore as these are specific to NDB for handling
      idempotency
     */
    break;
  }
  case HA_EXTRA_WRITE_CAN_REPLACE:
  case HA_EXTRA_WRITE_CANNOT_REPLACE:
  {
    /*
      Informs handler that write_row() can replace rows which conflict
      with row being inserted by PK/unique key without reporting error
      to the SQL-layer.

      This optimization is not safe for partitioned table in general case
      since we may have to put new version of row into partition which is
      different from partition in which old version resides (for example
      when we partition by non-PK column or by some column which is not
      part of unique key which were violated).
      And since NDB which is the only engine at the moment that supports
      this optimization handles partitioning on its own we simple disable
      it here. (BTW for NDB this optimization is safe since it supports
      only KEY partitioning and won't use this optimization for tables
      which have additional unique constraints).
    */
    break;
  }
    /* Category 7), used by federated handlers */
  case HA_EXTRA_INSERT_WITH_UPDATE:
    DBUG_RETURN(loop_extra(operation));
    /* Category 8) Parameters only used by NDB */
  case HA_EXTRA_DELETE_CANNOT_BATCH:
  case HA_EXTRA_UPDATE_CANNOT_BATCH:
  {
    /* Currently only NDB use the *_CANNOT_BATCH */
    break;
  }
  /*
    http://dev.mysql.com/doc/refman/5.1/en/partitioning-limitations.html
    says we no longer support logging to partitioned tables, so we fail
    here.
  */
  case HA_EXTRA_MARK_AS_LOG_TABLE:
    DBUG_RETURN(ER_UNSUPORTED_LOG_ENGINE);
  default:
  {
    /* Temporary crash to discover what is wrong */
    DBUG_ASSERT(0);
    break;
  }
  }
  DBUG_RETURN(0);
}


/*
  Special extra call to reset extra parameters

  SYNOPSIS
    reset()

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    Called at end of each statement to reste buffers
*/

int ha_partition::reset(void)
{
  int result= 0, tmp;
  handler **file;
  DBUG_ENTER("ha_partition::reset");
  if (m_part_info)
    bitmap_set_all(&m_part_info->used_partitions);
  file= m_file;
  do
  {
    if ((tmp= (*file)->ha_reset()))
      result= tmp;
  } while (*(++file));
  DBUG_RETURN(result);
}

/*
  Special extra method for HA_EXTRA_CACHE with cachesize as extra parameter

  SYNOPSIS
    extra_opt()
    operation                      Must be HA_EXTRA_CACHE
    cachesize                      Size of cache in full table scan

  RETURN VALUE
    >0                   Error code
    0                    Success
*/

int ha_partition::extra_opt(enum ha_extra_function operation, ulong cachesize)
{
  DBUG_ENTER("ha_partition::extra_opt()");

  DBUG_ASSERT(HA_EXTRA_CACHE == operation);
  prepare_extra_cache(cachesize);
  DBUG_RETURN(0);
}


/*
  Call extra on handler with HA_EXTRA_CACHE and cachesize

  SYNOPSIS
    prepare_extra_cache()
    cachesize                Size of cache for full table scan

  RETURN VALUE
    NONE
*/

void ha_partition::prepare_extra_cache(uint cachesize)
{
  DBUG_ENTER("ha_partition::prepare_extra_cache()");
  DBUG_PRINT("info", ("cachesize %u", cachesize));

  m_extra_cache= TRUE;
  m_extra_cache_size= cachesize;
  if (m_part_spec.start_part != NO_CURRENT_PART_ID)
  {
    late_extra_cache(m_part_spec.start_part);
  }
  DBUG_VOID_RETURN;
}


/*
  Prepares our new and reorged handlers for rename or delete

  SYNOPSIS
    prepare_for_delete()

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::prepare_for_rename()
{
  int result= 0, tmp;
  handler **file;
  DBUG_ENTER("ha_partition::prepare_for_rename()");
  
  if (m_new_file != NULL)
  {
    for (file= m_new_file; *file; file++)
      if ((tmp= (*file)->extra(HA_EXTRA_PREPARE_FOR_RENAME)))
        result= tmp;      
    for (file= m_reorged_file; *file; file++)
      if ((tmp= (*file)->extra(HA_EXTRA_PREPARE_FOR_RENAME)))
        result= tmp;   
    DBUG_RETURN(result);   
  }
  
  DBUG_RETURN(loop_extra(HA_EXTRA_PREPARE_FOR_RENAME));
}

/*
  Call extra on all partitions

  SYNOPSIS
    loop_extra()
    operation             extra operation type

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::loop_extra(enum ha_extra_function operation)
{
  int result= 0, tmp;
  handler **file;
  bool is_select;
  DBUG_ENTER("ha_partition::loop_extra()");
  
  is_select= (thd_sql_command(ha_thd()) == SQLCOM_SELECT);
  for (file= m_file; *file; file++)
  {
    if (!is_select ||
        bitmap_is_set(&(m_part_info->used_partitions), file - m_file))
    {
      if ((tmp= (*file)->extra(operation)))
        result= tmp;
    }
  }
  DBUG_RETURN(result);
}


/*
  Call extra(HA_EXTRA_CACHE) on next partition_id

  SYNOPSIS
    late_extra_cache()
    partition_id               Partition id to call extra on

  RETURN VALUE
    NONE
*/

void ha_partition::late_extra_cache(uint partition_id)
{
  handler *file;
  DBUG_ENTER("ha_partition::late_extra_cache");
  DBUG_PRINT("info", ("extra_cache %u prepare %u partid %u size %u",
                      m_extra_cache, m_extra_prepare_for_update,
                      partition_id, m_extra_cache_size));

  if (!m_extra_cache && !m_extra_prepare_for_update)
    DBUG_VOID_RETURN;
  file= m_file[partition_id];
  if (m_extra_cache)
  {
    if (m_extra_cache_size == 0)
      VOID(file->extra(HA_EXTRA_CACHE));
    else
      VOID(file->extra_opt(HA_EXTRA_CACHE, m_extra_cache_size));
  }
  if (m_extra_prepare_for_update)
  {
    VOID(file->extra(HA_EXTRA_PREPARE_FOR_UPDATE));
  }
  m_extra_cache_part_id= partition_id;
  DBUG_VOID_RETURN;
}


/*
  Call extra(HA_EXTRA_NO_CACHE) on next partition_id

  SYNOPSIS
    late_extra_no_cache()
    partition_id               Partition id to call extra on

  RETURN VALUE
    NONE
*/

void ha_partition::late_extra_no_cache(uint partition_id)
{
  handler *file;
  DBUG_ENTER("ha_partition::late_extra_no_cache");

  if (!m_extra_cache && !m_extra_prepare_for_update)
    DBUG_VOID_RETURN;
  file= m_file[partition_id];
  VOID(file->extra(HA_EXTRA_NO_CACHE));
  DBUG_ASSERT(partition_id == m_extra_cache_part_id);
  m_extra_cache_part_id= NO_CURRENT_PART_ID;
  DBUG_VOID_RETURN;
}


/****************************************************************************
                MODULE optimiser support
****************************************************************************/

/*
  Get keys to use for scanning

  SYNOPSIS
    keys_to_use_for_scanning()

  RETURN VALUE
    key_map of keys usable for scanning
*/

const key_map *ha_partition::keys_to_use_for_scanning()
{
  DBUG_ENTER("ha_partition::keys_to_use_for_scanning");

  DBUG_RETURN(m_file[0]->keys_to_use_for_scanning());
}

#define MAX_PARTS_FOR_OPTIMIZER_CALLS 10
/*
  Prepare start variables for estimating optimizer costs.

  @param[out] num_used_parts  Number of partitions after pruning.
  @param[out] check_min_num   Number of partitions to call.
  @param[out] first           first used partition.
*/
void ha_partition::partitions_optimizer_call_preparations(uint *first,
                                                          uint *num_used_parts,
                                                          uint *check_min_num)
{
  *first= bitmap_get_first_set(&(m_part_info->used_partitions));
  *num_used_parts= bitmap_bits_set(&(m_part_info->used_partitions));
  *check_min_num= min(MAX_PARTS_FOR_OPTIMIZER_CALLS, *num_used_parts);
}


/*
  Return time for a scan of the table

  SYNOPSIS
    scan_time()

  RETURN VALUE
    time for scan
*/

double ha_partition::scan_time()
{
  double scan_time= 0.0;
  uint first, part_id, num_used_parts, check_min_num, partitions_called= 0;
  DBUG_ENTER("ha_partition::scan_time");

  partitions_optimizer_call_preparations(&first, &num_used_parts, &check_min_num);
  for (part_id= first; partitions_called < num_used_parts ; part_id++)
  {
    if (!bitmap_is_set(&(m_part_info->used_partitions), part_id))
      continue;
    scan_time+= m_file[part_id]->scan_time();
    partitions_called++;
    if (partitions_called >= check_min_num && scan_time != 0.0)
    {
      DBUG_RETURN(scan_time *
                      (double) num_used_parts / (double) partitions_called);
    }
  }
  DBUG_RETURN(scan_time);
}


/*
  Estimate rows for records_in_range or estimate_rows_upper_bound.

  @param is_records_in_range  call records_in_range instead of
                              estimate_rows_upper_bound.
  @param inx                  (only for records_in_range) index to use.
  @param min_key              (only for records_in_range) start of range.
  @param max_key              (only for records_in_range) end of range.

  @return Number of rows or HA_POS_ERROR.
*/
ha_rows ha_partition::estimate_rows(bool is_records_in_range, uint inx,
                                    key_range *min_key, key_range *max_key)
{
  ha_rows rows, estimated_rows= 0;
  uint first, part_id, num_used_parts, check_min_num, partitions_called= 0;
  DBUG_ENTER("ha_partition::records_in_range");

  partitions_optimizer_call_preparations(&first, &num_used_parts, &check_min_num);
  for (part_id= first; partitions_called < num_used_parts ; part_id++)
  {
    if (!bitmap_is_set(&(m_part_info->used_partitions), part_id))
      continue;
    if (is_records_in_range)
      rows= m_file[part_id]->records_in_range(inx, min_key, max_key);
    else
      rows= m_file[part_id]->estimate_rows_upper_bound();
    if (rows == HA_POS_ERROR)
      DBUG_RETURN(HA_POS_ERROR);
    estimated_rows+= rows;
    partitions_called++;
    if (partitions_called >= check_min_num && estimated_rows)
    {
      DBUG_RETURN(estimated_rows * num_used_parts / partitions_called);
    }
  }
  DBUG_RETURN(estimated_rows);
}


/*
  Find number of records in a range

  SYNOPSIS
    records_in_range()
    inx                  Index number
    min_key              Start of range
    max_key              End of range

  RETURN VALUE
    Number of rows in range

  DESCRIPTION
    Given a starting key, and an ending key estimate the number of rows that
    will exist between the two. end_key may be empty which in case determine
    if start_key matches any rows.

    Called from opt_range.cc by check_quick_keys().

    monty: MUST be called for each range and added.
          Note that MySQL will assume that if this returns 0 there is no
          matching rows for the range!
*/

ha_rows ha_partition::records_in_range(uint inx, key_range *min_key,
				       key_range *max_key)
{
  DBUG_ENTER("ha_partition::records_in_range");

  DBUG_RETURN(estimate_rows(TRUE, inx, min_key, max_key));
}


/*
  Estimate upper bound of number of rows

  SYNOPSIS
    estimate_rows_upper_bound()

  RETURN VALUE
    Number of rows
*/

ha_rows ha_partition::estimate_rows_upper_bound()
{
  DBUG_ENTER("ha_partition::estimate_rows_upper_bound");

  DBUG_RETURN(estimate_rows(FALSE, 0, NULL, NULL));
}


/*
  Get time to read

  SYNOPSIS
    read_time()
    index                Index number used
    ranges               Number of ranges
    rows                 Number of rows

  RETURN VALUE
    time for read

  DESCRIPTION
    This will be optimised later to include whether or not the index can
    be used with partitioning. To achieve we need to add another parameter
    that specifies how many of the index fields that are bound in the ranges.
    Possibly added as a new call to handlers.
*/

double ha_partition::read_time(uint index, uint ranges, ha_rows rows)
{
  DBUG_ENTER("ha_partition::read_time");

  DBUG_RETURN(m_file[0]->read_time(index, ranges, rows));
}


/**
  Number of rows in table. see handler.h

  SYNOPSIS
    records()

  RETURN VALUE
    Number of total rows in a partitioned table.
*/

ha_rows ha_partition::records()
{
  ha_rows rows, tot_rows= 0;
  handler **file;
  DBUG_ENTER("ha_partition::records");

  file= m_file;
  do
  {
    rows= (*file)->records();
    if (rows == HA_POS_ERROR)
      DBUG_RETURN(HA_POS_ERROR);
    tot_rows+= rows;
  } while (*(++file));
  DBUG_RETURN(tot_rows);
}


/*
  Is it ok to switch to a new engine for this table

  SYNOPSIS
    can_switch_engine()

  RETURN VALUE
    TRUE                  Ok
    FALSE                 Not ok

  DESCRIPTION
    Used to ensure that tables with foreign key constraints are not moved
    to engines without foreign key support.
*/

bool ha_partition::can_switch_engines()
{
  handler **file;
  DBUG_ENTER("ha_partition::can_switch_engines");
 
  file= m_file;
  do
  {
    if (!(*file)->can_switch_engines())
      DBUG_RETURN(FALSE);
  } while (*(++file));
  DBUG_RETURN(TRUE);
}


/*
  Is table cache supported

  SYNOPSIS
    table_cache_type()

*/

uint8 ha_partition::table_cache_type()
{
  DBUG_ENTER("ha_partition::table_cache_type");

  DBUG_RETURN(m_file[0]->table_cache_type());
}


/****************************************************************************
                MODULE print messages
****************************************************************************/

const char *ha_partition::index_type(uint inx)
{
  DBUG_ENTER("ha_partition::index_type");

  DBUG_RETURN(m_file[0]->index_type(inx));
}


enum row_type ha_partition::get_row_type() const
{
  handler **file;
  enum row_type type= (*m_file)->get_row_type();

  for (file= m_file, file++; *file; file++)
  {
    enum row_type part_type= (*file)->get_row_type();
    if (part_type != type)
      return ROW_TYPE_NOT_USED;
  }

  return type;
}


void ha_partition::print_error(int error, myf errflag)
{
  DBUG_ENTER("ha_partition::print_error");

  /* Should probably look for my own errors first */
  DBUG_PRINT("enter", ("error: %d", error));

  if (error == HA_ERR_NO_PARTITION_FOUND)
    m_part_info->print_no_partition_found(table);
  else
  {
    /* In case m_file has not been initialized, like in bug#42438 */
    if (m_file)
    {
      if (m_last_part >= m_tot_parts)
      {
        DBUG_ASSERT(0);
        m_last_part= 0;
      }
      m_file[m_last_part]->print_error(error, errflag);
    }
    else
      handler::print_error(error, errflag);
  }
  DBUG_VOID_RETURN;
}


bool ha_partition::get_error_message(int error, String *buf)
{
  DBUG_ENTER("ha_partition::get_error_message");

  /* Should probably look for my own errors first */

  /* In case m_file has not been initialized, like in bug#42438 */
  if (m_file)
    DBUG_RETURN(m_file[m_last_part]->get_error_message(error, buf));
  DBUG_RETURN(handler::get_error_message(error, buf));

}


/****************************************************************************
                MODULE handler characteristics
****************************************************************************/
/**
  alter_table_flags must be on handler/table level, not on hton level
  due to the ha_partition hton does not know what the underlying hton is.
*/
uint ha_partition::alter_table_flags(uint flags)
{
  DBUG_ENTER("ha_partition::alter_table_flags");
  DBUG_RETURN(ht->alter_table_flags(flags) |
              m_file[0]->alter_table_flags(flags)); 
}


/**
  check if copy of data is needed in alter table.
*/
bool ha_partition::check_if_incompatible_data(HA_CREATE_INFO *create_info,
                                              uint table_changes)
{
  handler **file;
  bool ret= COMPATIBLE_DATA_YES;

  /*
    The check for any partitioning related changes have already been done
    in mysql_alter_table (by fix_partition_func), so it is only up to
    the underlying handlers.
  */
  for (file= m_file; *file; file++)
    if ((ret=  (*file)->check_if_incompatible_data(create_info,
                                                   table_changes)) !=
        COMPATIBLE_DATA_YES)
      break;
  return ret;
}


/**
  Support of fast or online add/drop index
*/
int ha_partition::add_index(TABLE *table_arg, KEY *key_info, uint num_of_keys)
{
  handler **file;
  int ret= 0;

  /*
    There has already been a check in fix_partition_func in mysql_alter_table
    before this call, which checks for unique/primary key violations of the
    partitioning function. So no need for extra check here.
  */
  for (file= m_file; *file; file++)
    if ((ret=  (*file)->add_index(table_arg, key_info, num_of_keys)))
      goto err;
  return ret;
err:
  if (file > m_file)
  {
    uint *key_numbers= (uint*) ha_thd()->alloc(sizeof(uint) * num_of_keys);
    KEY *old_key_info= table_arg->key_info;
    uint i;
    /* Use the newly added key_info as table->key_info to remove them. */
    for (i= 0; i < num_of_keys; i++)
      key_numbers[i]= i;
    table_arg->key_info= key_info;
    while (--file >= m_file)
    {
      (void) (*file)->prepare_drop_index(table_arg, key_numbers, num_of_keys);
      (void) (*file)->final_drop_index(table_arg);
    }
    table_arg->key_info= old_key_info;
  }
  return ret;
}


int ha_partition::prepare_drop_index(TABLE *table_arg, uint *key_num,
                                 uint num_of_keys)
{
  handler **file;
  int ret= 0;

  /*
    DROP INDEX does not affect partitioning.
  */
  for (file= m_file; *file; file++)
    if ((ret=  (*file)->prepare_drop_index(table_arg, key_num, num_of_keys)))
      break;
  return ret;
}


int ha_partition::final_drop_index(TABLE *table_arg)
{
  handler **file;
  int ret= HA_ERR_WRONG_COMMAND;

  for (file= m_file; *file; file++)
    if ((ret=  (*file)->final_drop_index(table_arg)))
      break;
  return ret;
}


/*
  If frm_error() is called then we will use this to to find out what file
  extensions exist for the storage engine. This is also used by the default
  rename_table and delete_table method in handler.cc.
*/

static const char *ha_partition_ext[]=
{
  ha_par_ext, NullS
};

const char **ha_partition::bas_ext() const
{ return ha_partition_ext; }


uint ha_partition::min_of_the_max_uint(
                       uint (handler::*operator_func)(void) const) const
{
  handler **file;
  uint min_of_the_max= ((*m_file)->*operator_func)();

  for (file= m_file+1; *file; file++)
  {
    uint tmp= ((*file)->*operator_func)();
    set_if_smaller(min_of_the_max, tmp);
  }
  return min_of_the_max;
}


uint ha_partition::max_supported_key_parts() const
{
  return min_of_the_max_uint(&handler::max_supported_key_parts);
}


uint ha_partition::max_supported_key_length() const
{
  return min_of_the_max_uint(&handler::max_supported_key_length);
}


uint ha_partition::max_supported_key_part_length() const
{
  return min_of_the_max_uint(&handler::max_supported_key_part_length);
}


uint ha_partition::max_supported_record_length() const
{
  return min_of_the_max_uint(&handler::max_supported_record_length);
}


uint ha_partition::max_supported_keys() const
{
  return min_of_the_max_uint(&handler::max_supported_keys);
}


uint ha_partition::extra_rec_buf_length() const
{
  handler **file;
  uint max= (*m_file)->extra_rec_buf_length();

  for (file= m_file, file++; *file; file++)
    if (max < (*file)->extra_rec_buf_length())
      max= (*file)->extra_rec_buf_length();
  return max;
}


uint ha_partition::min_record_length(uint options) const
{
  handler **file;
  uint max= (*m_file)->min_record_length(options);

  for (file= m_file, file++; *file; file++)
    if (max < (*file)->min_record_length(options))
      max= (*file)->min_record_length(options);
  return max;
}


/****************************************************************************
                MODULE compare records
****************************************************************************/
/*
  Compare two positions

  SYNOPSIS
    cmp_ref()
    ref1                   First position
    ref2                   Second position

  RETURN VALUE
    <0                     ref1 < ref2
    0                      Equal
    >0                     ref1 > ref2

  DESCRIPTION
    We get two references and need to check if those records are the same.
    If they belong to different partitions we decide that they are not
    the same record. Otherwise we use the particular handler to decide if
    they are the same. Sort in partition id order if not equal.
*/

int ha_partition::cmp_ref(const uchar *ref1, const uchar *ref2)
{
  uint part_id;
  my_ptrdiff_t diff1, diff2;
  handler *file;
  DBUG_ENTER("ha_partition::cmp_ref");

  if ((ref1[0] == ref2[0]) && (ref1[1] == ref2[1]))
  {
    part_id= uint2korr(ref1);
    file= m_file[part_id];
    DBUG_ASSERT(part_id < m_tot_parts);
    DBUG_RETURN(file->cmp_ref((ref1 + PARTITION_BYTES_IN_POS),
			      (ref2 + PARTITION_BYTES_IN_POS)));
  }
  diff1= ref2[1] - ref1[1];
  diff2= ref2[0] - ref1[0];
  if (diff1 > 0)
  {
    DBUG_RETURN(-1);
  }
  if (diff1 < 0)
  {
    DBUG_RETURN(+1);
  }
  if (diff2 > 0)
  {
    DBUG_RETURN(-1);
  }
  DBUG_RETURN(+1);
}


/****************************************************************************
                MODULE auto increment
****************************************************************************/


int ha_partition::reset_auto_increment(ulonglong value)
{
  handler **file= m_file;
  int res;
  HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
  DBUG_ENTER("ha_partition::reset_auto_increment");
  lock_auto_increment();
  ha_data->auto_inc_initialized= FALSE;
  ha_data->next_auto_inc_val= 0;
  do
  {
    if ((res= (*file)->ha_reset_auto_increment(value)) != 0)
      break;
  } while (*(++file));
  unlock_auto_increment();
  DBUG_RETURN(res);
}


/**
  This method is called by update_auto_increment which in turn is called
  by the individual handlers as part of write_row. We use the
  table_share->ha_data->next_auto_inc_val, or search all
  partitions for the highest auto_increment_value if not initialized or
  if auto_increment field is a secondary part of a key, we must search
  every partition when holding a mutex to be sure of correctness.
*/

void ha_partition::get_auto_increment(ulonglong offset, ulonglong increment,
                                      ulonglong nb_desired_values,
                                      ulonglong *first_value,
                                      ulonglong *nb_reserved_values)
{
  DBUG_ENTER("ha_partition::get_auto_increment");
  DBUG_PRINT("info", ("offset: %lu inc: %lu desired_values: %lu "
                      "first_value: %lu", (ulong) offset, (ulong) increment,
                      (ulong) nb_desired_values, (ulong) *first_value));
  DBUG_ASSERT(increment && nb_desired_values);
  *first_value= 0;
  if (table->s->next_number_keypart)
  {
    /*
      next_number_keypart is != 0 if the auto_increment column is a secondary
      column in the index (it is allowed in MyISAM)
    */
    DBUG_PRINT("info", ("next_number_keypart != 0"));
    ulonglong nb_reserved_values_part;
    ulonglong first_value_part, max_first_value;
    handler **file= m_file;
    first_value_part= max_first_value= *first_value;
    /* Must lock and find highest value among all partitions. */
    lock_auto_increment();
    do
    {
      /* Only nb_desired_values = 1 makes sense */
      (*file)->get_auto_increment(offset, increment, 1,
                                 &first_value_part, &nb_reserved_values_part);
      if (first_value_part == ~(ulonglong)(0)) // error in one partition
      {
        *first_value= first_value_part;
        /* log that the error was between table/partition handler */
        sql_print_error("Partition failed to reserve auto_increment value");
        unlock_auto_increment();
        DBUG_VOID_RETURN;
      }
      DBUG_PRINT("info", ("first_value_part: %lu", (ulong) first_value_part));
      set_if_bigger(max_first_value, first_value_part);
    } while (*(++file));
    *first_value= max_first_value;
    *nb_reserved_values= 1;
    unlock_auto_increment();
  }
  else
  {
    THD *thd= ha_thd();
    HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
    /*
      This is initialized in the beginning of the first write_row call.
    */
    DBUG_ASSERT(ha_data->auto_inc_initialized);
    /*
      Get a lock for handling the auto_increment in table_share->ha_data
      for avoiding two concurrent statements getting the same number.
    */ 

    lock_auto_increment();

    /*
      In a multi-row insert statement like INSERT SELECT and LOAD DATA
      where the number of candidate rows to insert is not known in advance
      we must hold a lock/mutex for the whole statement if we have statement
      based replication. Because the statement-based binary log contains
      only the first generated value used by the statement, and slaves assumes
      all other generated values used by this statement were consecutive to
      this first one, we must exclusively lock the generator until the statement
      is done.
    */
    if (!auto_increment_safe_stmt_log_lock &&
        thd->lex->sql_command != SQLCOM_INSERT &&
        mysql_bin_log.is_open() &&
        !thd->current_stmt_binlog_row_based &&
        (thd->options & OPTION_BIN_LOG))
    {
      DBUG_PRINT("info", ("locking auto_increment_safe_stmt_log_lock"));
      auto_increment_safe_stmt_log_lock= TRUE;
    }

    /* this gets corrected (for offset/increment) in update_auto_increment */
    *first_value= ha_data->next_auto_inc_val;
    ha_data->next_auto_inc_val+= nb_desired_values * increment;

    unlock_auto_increment();
    DBUG_PRINT("info", ("*first_value: %lu", (ulong) *first_value));
    *nb_reserved_values= nb_desired_values;
  }
  DBUG_VOID_RETURN;
}

void ha_partition::release_auto_increment()
{
  DBUG_ENTER("ha_partition::release_auto_increment");

  if (table->s->next_number_keypart)
  {
    for (uint i= 0; i < m_tot_parts; i++)
      m_file[i]->ha_release_auto_increment();
  }
  else if (next_insert_id)
  {
    HA_DATA_PARTITION *ha_data= (HA_DATA_PARTITION*) table_share->ha_data;
    ulonglong next_auto_inc_val;
    lock_auto_increment();
    next_auto_inc_val= ha_data->next_auto_inc_val;
    /*
      If the current auto_increment values is lower than the reserved
      value, and the reserved value was reserved by this thread,
      we can lower the reserved value.
    */
    if (next_insert_id < next_auto_inc_val &&
        auto_inc_interval_for_cur_row.maximum() >= next_auto_inc_val)
    {
      THD *thd= ha_thd();
      /*
        Check that we do not lower the value because of a failed insert
        with SET INSERT_ID, i.e. forced/non generated values.
      */
      if (thd->auto_inc_intervals_forced.maximum() < next_insert_id)
        ha_data->next_auto_inc_val= next_insert_id;
    }
    DBUG_PRINT("info", ("ha_data->next_auto_inc_val: %lu",
                        (ulong) ha_data->next_auto_inc_val));

    /* Unlock the multi row statement lock taken in get_auto_increment */
    if (auto_increment_safe_stmt_log_lock)
    {
      auto_increment_safe_stmt_log_lock= FALSE;
      DBUG_PRINT("info", ("unlocking auto_increment_safe_stmt_log_lock"));
    }

    unlock_auto_increment();
  }
  DBUG_VOID_RETURN;
}

/****************************************************************************
                MODULE initialize handler for HANDLER call
****************************************************************************/

void ha_partition::init_table_handle_for_HANDLER()
{
  return;
}


/****************************************************************************
                MODULE enable/disable indexes
****************************************************************************/

/*
  Disable indexes for a while
  SYNOPSIS
    disable_indexes()
    mode                      Mode
  RETURN VALUES
    0                         Success
    != 0                      Error
*/

int ha_partition::disable_indexes(uint mode)
{
  handler **file;
  int error= 0;

  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->ha_disable_indexes(mode)))
      break;
  }
  return error;
}


/*
  Enable indexes again
  SYNOPSIS
    enable_indexes()
    mode                      Mode
  RETURN VALUES
    0                         Success
    != 0                      Error
*/

int ha_partition::enable_indexes(uint mode)
{
  handler **file;
  int error= 0;

  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->ha_enable_indexes(mode)))
      break;
  }
  return error;
}


/*
  Check if indexes are disabled
  SYNOPSIS
    indexes_are_disabled()

  RETURN VALUES
    0                      Indexes are enabled
    != 0                   Indexes are disabled
*/

int ha_partition::indexes_are_disabled(void)
{
  handler **file;
  int error= 0;

  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->indexes_are_disabled()))
      break;
  }
  return error;
}


/****************************************************************************
                MODULE Partition Share
****************************************************************************/
/*
  Service routines for ... methods.
-------------------------------------------------------------------------
  Variables for partition share methods. A hash used to track open tables.
  A mutex for the hash table and an init variable to check if hash table
  is initialized.
  There is also a constant ending of the partition handler file name.
*/

#ifdef NOT_USED
static HASH partition_open_tables;
static pthread_mutex_t partition_mutex;
static int partition_init= 0;


/*
  Function we use in the creation of our hash to get key.
*/

static uchar *partition_get_key(PARTITION_SHARE *share, size_t *length,
			       my_bool not_used __attribute__ ((unused)))
{
  *length= share->table_name_length;
  return (uchar *) share->table_name;
}

/*
  Example of simple lock controls. The "share" it creates is structure we
  will pass to each partition handler. Do you have to have one of these?
  Well, you have pieces that are used for locking, and they are needed to
  function.
*/

static PARTITION_SHARE *get_share(const char *table_name, TABLE *table)
{
  PARTITION_SHARE *share;
  uint length;
  char *tmp_name;

  /*
    So why does this exist? There is no way currently to init a storage
    engine.
    Innodb and BDB both have modifications to the server to allow them to
    do this. Since you will not want to do this, this is probably the next
    best method.
  */
  if (!partition_init)
  {
    /* Hijack a mutex for init'ing the storage engine */
    pthread_mutex_lock(&LOCK_mysql_create_db);
    if (!partition_init)
    {
      partition_init++;
      VOID(pthread_mutex_init(&partition_mutex, MY_MUTEX_INIT_FAST));
      (void) hash_init(&partition_open_tables, system_charset_info, 32, 0, 0,
		       (hash_get_key) partition_get_key, 0, 0);
    }
    pthread_mutex_unlock(&LOCK_mysql_create_db);
  }
  pthread_mutex_lock(&partition_mutex);
  length= (uint) strlen(table_name);

  if (!(share= (PARTITION_SHARE *) hash_search(&partition_open_tables,
					       (uchar *) table_name, length)))
  {
    if (!(share= (PARTITION_SHARE *)
	  my_multi_malloc(MYF(MY_WME | MY_ZEROFILL),
			  &share, (uint) sizeof(*share),
			  &tmp_name, (uint) length + 1, NullS)))
    {
      pthread_mutex_unlock(&partition_mutex);
      return NULL;
    }

    share->use_count= 0;
    share->table_name_length= length;
    share->table_name= tmp_name;
    strmov(share->table_name, table_name);
    if (my_hash_insert(&partition_open_tables, (uchar *) share))
      goto error;
    thr_lock_init(&share->lock);
    pthread_mutex_init(&share->mutex, MY_MUTEX_INIT_FAST);
  }
  share->use_count++;
  pthread_mutex_unlock(&partition_mutex);

  return share;

error:
  pthread_mutex_unlock(&partition_mutex);
  my_free((uchar*) share, MYF(0));

  return NULL;
}


/*
  Free lock controls. We call this whenever we close a table. If the table
  had the last reference to the share then we free memory associated with
  it.
*/

static int free_share(PARTITION_SHARE *share)
{
  pthread_mutex_lock(&partition_mutex);
  if (!--share->use_count)
  {
    hash_delete(&partition_open_tables, (uchar *) share);
    thr_lock_delete(&share->lock);
    pthread_mutex_destroy(&share->mutex);
    my_free((uchar*) share, MYF(0));
  }
  pthread_mutex_unlock(&partition_mutex);

  return 0;
}
#endif /* NOT_USED */

struct st_mysql_storage_engine partition_storage_engine=
{ MYSQL_HANDLERTON_INTERFACE_VERSION };

mysql_declare_plugin(partition)
{
  MYSQL_STORAGE_ENGINE_PLUGIN,
  &partition_storage_engine,
  "partition",
  "Mikael Ronstrom, MySQL AB",
  "Partition Storage Engine Helper",
  PLUGIN_LICENSE_GPL,
  partition_initialize, /* Plugin Init */
  NULL, /* Plugin Deinit */
  0x0100, /* 1.0 */
  NULL,                       /* status variables                */
  NULL,                       /* system variables                */
  NULL                        /* config options                  */
}
mysql_declare_plugin_end;

#endif