path: root/sql/sql_lex.h

/* Copyright (c) 2000, 2014, Oracle and/or its affiliates.
   Copyright (c) 2010, 2015, MariaDB

   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 */

/**
  @defgroup Semantic_Analysis Semantic Analysis
*/

#ifndef SQL_LEX_INCLUDED
#define SQL_LEX_INCLUDED

#include "violite.h"                            /* SSL_type */
#include "sql_trigger.h"
#include "item.h"               /* From item_subselect.h: subselect_union_engine */
#include "thr_lock.h"                  /* thr_lock_type, TL_UNLOCK */
#include "mem_root_array.h"
#include "sql_cmd.h"
#include "sql_alter.h"                // Alter_info

/* YACC and LEX Definitions */

/* These may not be declared yet */
class Table_ident;
class sql_exchange;
class LEX_COLUMN;
class sp_head;
class sp_name;
class sp_instr;
class sp_pcontext;
class st_alter_tablespace;
class partition_info;
class Event_parse_data;
class set_var_base;
class sys_var;
class Item_func_match;
class File_parser;
class Key_part_spec;
struct sql_digest_state;

#define ALLOC_ROOT_SET 1024

#ifdef MYSQL_SERVER
/*
  There are 8 different type of table access so there is no more than
  combinations 2^8 = 256:

  . STMT_READS_TRANS_TABLE

  . STMT_READS_NON_TRANS_TABLE

  . STMT_READS_TEMP_TRANS_TABLE

  . STMT_READS_TEMP_NON_TRANS_TABLE

  . STMT_WRITES_TRANS_TABLE

  . STMT_WRITES_NON_TRANS_TABLE

  . STMT_WRITES_TEMP_TRANS_TABLE

  . STMT_WRITES_TEMP_NON_TRANS_TABLE

  The unsafe conditions for each combination is represented within a byte
  and stores the status of the option --binlog-direct-non-trans-updates,
  whether the trx-cache is empty or not, and whether the isolation level
  is lower than ISO_REPEATABLE_READ:

  . option (OFF/ON)
  . trx-cache (empty/not empty)
  . isolation (>= ISO_REPEATABLE_READ / < ISO_REPEATABLE_READ)

  bits 0 : . OFF, . empty, . >= ISO_REPEATABLE_READ
  bits 1 : . OFF, . empty, . < ISO_REPEATABLE_READ
  bits 2 : . OFF, . not empty, . >= ISO_REPEATABLE_READ
  bits 3 : . OFF, . not empty, . < ISO_REPEATABLE_READ
  bits 4 : . ON, . empty, . >= ISO_REPEATABLE_READ
  bits 5 : . ON, . empty, . < ISO_REPEATABLE_READ
  bits 6 : . ON, . not empty, . >= ISO_REPEATABLE_READ
  bits 7 : . ON, . not empty, . < ISO_REPEATABLE_READ
*/
extern uint binlog_unsafe_map[256];
/*
  Initializes the array with unsafe combinations and its respective
  conditions.
*/
void binlog_unsafe_map_init();
#endif

/**
  used by the parser to store internal variable name
*/
struct sys_var_with_base
{
  sys_var *var;
  LEX_STRING base_name;
};

struct LEX_TYPE
{
  enum enum_field_types type;
  char *length, *dec;
  CHARSET_INFO *charset;
  void set(int t, char *l, char *d, CHARSET_INFO *cs)
  { type= (enum_field_types)t; length= l; dec= d; charset= cs; }
};

#ifdef MYSQL_SERVER
/*
  The following hack is needed because mysql_yacc.cc does not define
  YYSTYPE before including this file
*/
#ifdef MYSQL_YACC
#define LEX_YYSTYPE void *
#else
#include "lex_symbol.h"
#if MYSQL_LEX
#include "item_func.h"            /* Cast_target used in sql_yacc.h */
#include "sql_get_diagnostics.h"  /* Types used in sql_yacc.h */
#include "sp_pcontext.h"
#include "sql_yacc.h"
#define LEX_YYSTYPE YYSTYPE *
#else
#define LEX_YYSTYPE void *
#endif
#endif
#endif

// describe/explain types
#define DESCRIBE_NORMAL		1
#define DESCRIBE_EXTENDED	2
/*
  This is not within #ifdef because we want "EXPLAIN PARTITIONS ..." to produce
  additional "partitions" column even if partitioning is not compiled in.
*/
#define DESCRIBE_PARTITIONS	4

#ifdef MYSQL_SERVER

extern const LEX_STRING null_lex_str;
extern const LEX_STRING empty_lex_str;

enum enum_sp_suid_behaviour
{
  SP_IS_DEFAULT_SUID= 0,
  SP_IS_NOT_SUID,
  SP_IS_SUID
};

enum enum_sp_data_access
{
  SP_DEFAULT_ACCESS= 0,
  SP_CONTAINS_SQL,
  SP_NO_SQL,
  SP_READS_SQL_DATA,
  SP_MODIFIES_SQL_DATA
};

const LEX_STRING sp_data_access_name[]=
{
  { C_STRING_WITH_LEN("") },
  { C_STRING_WITH_LEN("CONTAINS SQL") },
  { C_STRING_WITH_LEN("NO SQL") },
  { C_STRING_WITH_LEN("READS SQL DATA") },
  { C_STRING_WITH_LEN("MODIFIES SQL DATA") }
};

#define DERIVED_SUBQUERY	1
#define DERIVED_VIEW		2

enum enum_view_create_mode
{
  VIEW_CREATE_NEW,		// check that there are not such VIEW/table
  VIEW_ALTER,			// check that VIEW .frm with such name exists
  VIEW_CREATE_OR_REPLACE	// check only that there are not such table
};

enum enum_drop_mode
{
  DROP_DEFAULT, // mode is not specified
  DROP_CASCADE, // CASCADE option
  DROP_RESTRICT // RESTRICT option
};

/* Options to add_table_to_list() */
#define TL_OPTION_UPDATING	1
#define TL_OPTION_FORCE_INDEX	2
#define TL_OPTION_IGNORE_LEAVES 4
#define TL_OPTION_ALIAS         8

typedef List<Item> List_item;
typedef Mem_root_array<ORDER*, true> Group_list_ptrs;

/* SERVERS CACHE CHANGES */
typedef struct st_lex_server_options
{
  long port;
  LEX_STRING server_name, host, db, username, password, scheme, socket, owner;
  void reset(LEX_STRING name)
  {
    server_name= name;
    host= db= username= password= scheme= socket= owner= null_lex_str;
    port= -1;
  }
} LEX_SERVER_OPTIONS;


/**
  Structure to hold parameters for CHANGE MASTER, START SLAVE, and STOP SLAVE.

  Remark: this should not be confused with Master_info (and perhaps
  would better be renamed to st_lex_replication_info).  Some fields,
  e.g., delay, are saved in Relay_log_info, not in Master_info.
*/
struct LEX_MASTER_INFO
{
  DYNAMIC_ARRAY repl_ignore_server_ids;
  DYNAMIC_ARRAY repl_do_domain_ids;
  DYNAMIC_ARRAY repl_ignore_domain_ids;
  char *host, *user, *password, *log_file_name;
  char *ssl_key, *ssl_cert, *ssl_ca, *ssl_capath, *ssl_cipher;
  char *ssl_crl, *ssl_crlpath;
  char *relay_log_name;
  LEX_STRING connection_name;
  /* Value in START SLAVE UNTIL master_gtid_pos=xxx */
  LEX_STRING gtid_pos_str;
  ulonglong pos;
  ulong relay_log_pos;
  ulong server_id;
  uint port, connect_retry;
  float heartbeat_period;
  /*
    Enum is used for making it possible to detect if the user
    changed variable or if it should be left at old value
   */
  enum {LEX_MI_UNCHANGED, LEX_MI_DISABLE, LEX_MI_ENABLE}
    ssl, ssl_verify_server_cert, heartbeat_opt, repl_ignore_server_ids_opt,
    repl_do_domain_ids_opt, repl_ignore_domain_ids_opt;
  enum {
    LEX_GTID_UNCHANGED, LEX_GTID_NO, LEX_GTID_CURRENT_POS, LEX_GTID_SLAVE_POS
  } use_gtid_opt;

  void init()
  {
    bzero(this, sizeof(*this));
    my_init_dynamic_array(&repl_ignore_server_ids,
                          sizeof(::server_id), 0, 16, MYF(0));
    my_init_dynamic_array(&repl_do_domain_ids,
                          sizeof(ulong), 0, 16, MYF(0));
    my_init_dynamic_array(&repl_ignore_domain_ids,
                          sizeof(ulong), 0, 16, MYF(0));
  }
  void reset(bool is_change_master)
  {
    if (unlikely(is_change_master))
    {
      delete_dynamic(&repl_ignore_server_ids);
      /* Free all the array elements. */
      delete_dynamic(&repl_do_domain_ids);
      delete_dynamic(&repl_ignore_domain_ids);
    }

    host= user= password= log_file_name= ssl_key= ssl_cert= ssl_ca=
      ssl_capath= ssl_cipher= relay_log_name= 0;
    pos= relay_log_pos= server_id= port= connect_retry= 0;
    heartbeat_period= 0;
    ssl= ssl_verify_server_cert= heartbeat_opt=
      repl_ignore_server_ids_opt= repl_do_domain_ids_opt=
      repl_ignore_domain_ids_opt= LEX_MI_UNCHANGED;
    gtid_pos_str= null_lex_str;
    use_gtid_opt= LEX_GTID_UNCHANGED;
  }
};

typedef struct st_lex_reset_slave
{
  bool all;
} LEX_RESET_SLAVE;

enum sub_select_type
{
  UNSPECIFIED_TYPE,UNION_TYPE, INTERSECT_TYPE,
  EXCEPT_TYPE, GLOBAL_OPTIONS_TYPE, DERIVED_TABLE_TYPE, OLAP_TYPE
};

enum olap_type 
{
  UNSPECIFIED_OLAP_TYPE, CUBE_TYPE, ROLLUP_TYPE
};

/* 
  String names used to print a statement with index hints.
  Keep in sync with index_hint_type.
*/
extern const char * index_hint_type_name[];
typedef uchar index_clause_map;

/*
  Bits in index_clause_map : one for each possible FOR clause in
  USE/FORCE/IGNORE INDEX index hint specification
*/
#define INDEX_HINT_MASK_JOIN  (1)
#define INDEX_HINT_MASK_GROUP (1 << 1)
#define INDEX_HINT_MASK_ORDER (1 << 2)

#define INDEX_HINT_MASK_ALL (INDEX_HINT_MASK_JOIN | INDEX_HINT_MASK_GROUP | \
                             INDEX_HINT_MASK_ORDER)

class select_result_sink;

/* Single element of an USE/FORCE/IGNORE INDEX list specified as a SQL hint  */
class Index_hint : public Sql_alloc
{
public:
  /* The type of the hint : USE/FORCE/IGNORE */
  enum index_hint_type type;
  /* Where the hit applies to. A bitmask of INDEX_HINT_MASK_<place> values */
  index_clause_map clause;
  /* 
    The index name. Empty (str=NULL) name represents an empty list 
    USE INDEX () clause 
  */ 
  LEX_STRING key_name;

  Index_hint (enum index_hint_type type_arg, index_clause_map clause_arg,
              char *str, uint length) :
    type(type_arg), clause(clause_arg)
  {
    key_name.str= str;
    key_name.length= length;
  }

  void print(THD *thd, String *str);
}; 

/* 
  The state of the lex parsing for selects 
   
   master and slaves are pointers to select_lex.
   master is pointer to upper level node.
   slave is pointer to lower level node
   select_lex is a SELECT without union
   unit is container of either
     - One SELECT
     - UNION of selects
   select_lex and unit are both inherited form select_lex_node
   neighbors are two select_lex or units on the same level

   All select describing structures linked with following pointers:
   - list of neighbors (next/prev) (prev of first element point to slave
     pointer of upper structure)
     - For select this is a list of UNION's (or one element list)
     - For units this is a list of sub queries for the upper level select

   - pointer to master (master), which is
     If this is a unit
       - pointer to outer select_lex
     If this is a select_lex
       - pointer to outer unit structure for select

   - pointer to slave (slave), which is either:
     If this is a unit:
       - first SELECT that belong to this unit
     If this is a select_lex
       - first unit that belong to this SELECT (subquries or derived tables)

   - list of all select_lex (link_next/link_prev)
     This is to be used for things like derived tables creation, where we
     go through this list and create the derived tables.

   If unit contain several selects (UNION now, INTERSECT etc later)
   then it have special select_lex called fake_select_lex. It used for
   storing global parameters (like ORDER BY, LIMIT) and executing union.
   Subqueries used in global ORDER BY clause will be attached to this
   fake_select_lex, which will allow them correctly resolve fields of
   'upper' UNION and outer selects.

   For example for following query:

   select *
     from table1
     where table1.field IN (select * from table1_1_1 union
                            select * from table1_1_2)
     union
   select *
     from table2
     where table2.field=(select (select f1 from table2_1_1_1_1
                                   where table2_1_1_1_1.f2=table2_1_1.f3)
                           from table2_1_1
                           where table2_1_1.f1=table2.f2)
     union
   select * from table3;

   we will have following structure:

   select1: (select * from table1 ...)
   select2: (select * from table2 ...)
   select3: (select * from table3)
   select1.1.1: (select * from table1_1_1)
   ...

     main unit
     fake0
     select1 select2 select3
     |^^     |^
    s|||     ||master
    l|||     |+---------------------------------+
    a|||     +---------------------------------+|
    v|||master                         slave   ||
    e||+-------------------------+             ||
     V|            neighbor      |             V|
     unit1.1<+==================>unit1.2       unit2.1
     fake1.1
     select1.1.1 select 1.1.2    select1.2.1   select2.1.1
                                               |^
                                               ||
                                               V|
                                               unit2.1.1.1
                                               select2.1.1.1.1


   relation in main unit will be following:
   (bigger picture for:
      main unit
      fake0
      select1 select2 select3
   in the above picture)

         main unit
         |^^^^|fake_select_lex
         |||||+--------------------------------------------+
         ||||+--------------------------------------------+|
         |||+------------------------------+              ||
         ||+--------------+                |              ||
    slave||master         |                |              ||
         V|      neighbor |       neighbor |        master|V
         select1<========>select2<========>select3        fake0

    list of all select_lex will be following (as it will be constructed by
    parser):

    select1->select2->select3->select2.1.1->select 2.1.2->select2.1.1.1.1-+
                                                                          |
    +---------------------------------------------------------------------+
    |
    +->select1.1.1->select1.1.2

*/

/* 
    Base class for st_select_lex (SELECT_LEX) & 
    st_select_lex_unit (SELECT_LEX_UNIT)
*/
struct LEX;
class st_select_lex;
class st_select_lex_unit;


class st_select_lex_node {
protected:
  st_select_lex_node *next, **prev,   /* neighbor list */
    *master, *slave,                  /* vertical links */
    *link_next, **link_prev;          /* list of whole SELECT_LEX */
public:

  ulonglong options;

  /*
    In sql_cache we store SQL_CACHE flag as specified by user to be
    able to restore SELECT statement from internal structures.
  */
  enum e_sql_cache { SQL_CACHE_UNSPECIFIED, SQL_NO_CACHE, SQL_CACHE };
  e_sql_cache sql_cache;

  /*
    result of this query can't be cached, bit field, can be :
      UNCACHEABLE_DEPENDENT_GENERATED
      UNCACHEABLE_DEPENDENT_INJECTED
      UNCACHEABLE_RAND
      UNCACHEABLE_SIDEEFFECT
      UNCACHEABLE_EXPLAIN
      UNCACHEABLE_PREPARE
  */
  uint8 uncacheable;
  enum sub_select_type linkage;
  bool no_table_names_allowed; /* used for global order by */

  static void *operator new(size_t size) throw ()
  {
    return sql_alloc(size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
  { return (void*) alloc_root(mem_root, (uint) size); }
  static void operator delete(void *ptr,size_t size) { TRASH(ptr, size); }
  static void operator delete(void *ptr, MEM_ROOT *mem_root) {}

  // Ensures that at least all members used during cleanup() are initialized.
  st_select_lex_node()
    : next(NULL), prev(NULL),
      master(NULL), slave(NULL),
      link_next(NULL), link_prev(NULL),
      linkage(UNSPECIFIED_TYPE)
  {
  }
  virtual ~st_select_lex_node() {}

  inline st_select_lex_node* get_master() { return master; }
  virtual void init_query();
  virtual void init_select();
  void include_down(st_select_lex_node *upper);
  void add_slave(st_select_lex_node *slave_arg);
  void include_neighbour(st_select_lex_node *before);
  void include_standalone(st_select_lex_node *sel, st_select_lex_node **ref);
  void include_global(st_select_lex_node **plink);
  void exclude();
  void exclude_from_tree();

  virtual st_select_lex* outer_select()= 0;
  virtual st_select_lex* return_after_parsing()= 0;

  virtual bool set_braces(bool value);
  virtual bool inc_in_sum_expr();
  virtual uint get_in_sum_expr();
  virtual TABLE_LIST* get_table_list();
  virtual List<Item>* get_item_list();
  virtual ulong get_table_join_options();
  virtual TABLE_LIST *add_table_to_list(THD *thd, Table_ident *table,
					LEX_STRING *alias,
					ulong table_options,
					thr_lock_type flags= TL_UNLOCK,
                                        enum_mdl_type mdl_type= MDL_SHARED_READ,
					List<Index_hint> *hints= 0,
                                        List<String> *partition_names= 0,
                                        LEX_STRING *option= 0);
  virtual void set_lock_for_tables(thr_lock_type lock_type) {}

  friend class st_select_lex_unit;
  friend bool mysql_new_select(LEX *lex, bool move_down);
  friend bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
                              bool open_view_no_parse);
  friend bool mysql_derived_prepare(THD *thd, LEX *lex,
                                  TABLE_LIST *orig_table_list);
  friend bool mysql_derived_merge(THD *thd, LEX *lex,
                                  TABLE_LIST *orig_table_list);
  friend bool TABLE_LIST::init_derived(THD *thd, bool init_view);
private:
  void fast_exclude();
};
typedef class st_select_lex_node SELECT_LEX_NODE;

/* 
   SELECT_LEX_UNIT - unit of selects (UNION, INTERSECT, ...) group 
   SELECT_LEXs
*/
class THD;
class select_result;
class JOIN;
class select_union;
class Procedure;
class Explain_query;

void delete_explain_query(LEX *lex);
void create_explain_query(LEX *lex, MEM_ROOT *mem_root);
void create_explain_query_if_not_exists(LEX *lex, MEM_ROOT *mem_root);
bool print_explain_for_slow_log(LEX *lex, THD *thd, String *str);

class st_select_lex_unit: public st_select_lex_node {
protected:
  TABLE_LIST result_table_list;
  select_union *union_result;
  ulonglong found_rows_for_union;
  bool saved_error;

public:
  // Ensures that at least all members used during cleanup() are initialized.
  st_select_lex_unit()
    : union_result(NULL), table(NULL), result(NULL),
      cleaned(false),
      fake_select_lex(NULL)
  {
  }


  TABLE *table; /* temporary table using for appending UNION results */
  select_result *result;
  bool  prepared, // prepare phase already performed for UNION (unit)
    optimized, // optimize phase already performed for UNION (unit)
    executed, // already executed
    cleaned;

  // list of fields which points to temporary table for union
  List<Item> item_list;
  /*
    list of types of items inside union (used for union & derived tables)
    
    Item_type_holders from which this list consist may have pointers to Field,
    pointers is valid only after preparing SELECTS of this unit and before
    any SELECT of this unit execution
  */
  List<Item> types;
  /**
    Pointer to 'last' select, or pointer to select where we stored
    global parameters for union.

    If this is a union of multiple selects, the parser puts the global
    parameters in fake_select_lex. If the union doesn't use a
    temporary table, st_select_lex_unit::prepare() nulls out
    fake_select_lex, but saves a copy in saved_fake_select_lex in
    order to preserve the global parameters.

    If it is not a union, first_select() is the last select.

    @return select containing the global parameters
  */
  inline st_select_lex *global_parameters()
  {
    if (fake_select_lex != NULL)
      return fake_select_lex;
    else if (saved_fake_select_lex != NULL)
      return saved_fake_select_lex;
    return first_select();
  };
  //node on wich we should return current_select pointer after parsing subquery
  st_select_lex *return_to;
  /* LIMIT clause runtime counters */
  ha_rows select_limit_cnt, offset_limit_cnt;
  /* not NULL if unit used in subselect, point to subselect item */
  Item_subselect *item;
  /*
    TABLE_LIST representing this union in the embedding select. Used for
    derived tables/views handling.
  */
  TABLE_LIST *derived;
  /* thread handler */
  THD *thd;
  /*
    SELECT_LEX for hidden SELECT in onion which process global
    ORDER BY and LIMIT
  */
  st_select_lex *fake_select_lex;
  /**
    SELECT_LEX that stores LIMIT and OFFSET for UNION ALL when no
    fake_select_lex is used.
  */
  st_select_lex *saved_fake_select_lex;

  st_select_lex *union_distinct; /* pointer to the last UNION DISTINCT */
  bool describe; /* union exec() called for EXPLAIN */
  Procedure *last_procedure;	 /* Pointer to procedure, if such exists */

  /* 
    Insert table with stored virtual columns.
    This is used only in those rare cases 
    when the list of inserted values is empty.
  */
  TABLE *insert_table_with_stored_vcol;

  void init_query();
  st_select_lex* outer_select();
  st_select_lex* first_select()
  {
    return reinterpret_cast<st_select_lex*>(slave);
  }
  st_select_lex_unit* next_unit()
  {
    return reinterpret_cast<st_select_lex_unit*>(next);
  }
  st_select_lex* return_after_parsing() { return return_to; }
  void exclude_level();
  void exclude_tree();

  /* UNION methods */
  bool prepare(THD *thd, select_result *result, ulong additional_options);
  bool optimize();
  bool exec();
  bool cleanup();
  inline void unclean() { cleaned= 0; }
  void reinit_exec_mechanism();

  void print(String *str, enum_query_type query_type);

  bool add_fake_select_lex(THD *thd);
  void init_prepare_fake_select_lex(THD *thd, bool first_execution);
  inline bool is_prepared() { return prepared; }
  bool change_result(select_result_interceptor *result,
                     select_result_interceptor *old_result);
  void set_limit(st_select_lex *values);
  void set_thd(THD *thd_arg) { thd= thd_arg; }
  inline bool is_union (); 
  bool union_needs_tmp_table();

  void set_unique_exclude();

  friend void lex_start(THD *thd);
  friend int subselect_union_engine::exec();

  List<Item> *get_unit_column_types();

  select_union *get_union_result() { return union_result; }
  int save_union_explain(Explain_query *output);
  int save_union_explain_part2(Explain_query *output);
};

typedef class st_select_lex_unit SELECT_LEX_UNIT;

/*
  SELECT_LEX - store information of parsed SELECT statment
*/
class st_select_lex: public st_select_lex_node
{
public:
  Name_resolution_context context;
  char *db;
  Item *where, *having;                         /* WHERE & HAVING clauses */
  Item *prep_where; /* saved WHERE clause for prepared statement processing */
  Item *prep_having;/* saved HAVING clause for prepared statement processing */
  /* Saved values of the WHERE and HAVING clauses*/
  Item::cond_result cond_value, having_value;
  /* point on lex in which it was created, used in view subquery detection */
  LEX *parent_lex;
  enum olap_type olap;
  /* FROM clause - points to the beginning of the TABLE_LIST::next_local list. */
  SQL_I_List<TABLE_LIST>  table_list;

  /*
    GROUP BY clause.
    This list may be mutated during optimization (by remove_const()),
    so for prepared statements, we keep a copy of the ORDER.next pointers in
    group_list_ptrs, and re-establish the original list before each execution.
  */
  SQL_I_List<ORDER>       group_list;
  Group_list_ptrs        *group_list_ptrs;

  List<Item>          item_list;  /* list of fields & expressions */
  List<String>        interval_list;
  bool	              is_item_list_lookup;
  /* 
    Usualy it is pointer to ftfunc_list_alloc, but in union used to create fake
    select_lex for calling mysql_select under results of union
  */
  List<Item_func_match> *ftfunc_list;
  List<Item_func_match> ftfunc_list_alloc;
  JOIN *join; /* after JOIN::prepare it is pointer to corresponding JOIN */
  List<TABLE_LIST> top_join_list; /* join list of the top level          */
  List<TABLE_LIST> *join_list;    /* list for the currently parsed join  */
  TABLE_LIST *embedding;          /* table embedding to the above list   */
  List<TABLE_LIST> sj_nests;      /* Semi-join nests within this join */
  /*
    Beginning of the list of leaves in a FROM clause, where the leaves
    inlcude all base tables including view tables. The tables are connected
    by TABLE_LIST::next_leaf, so leaf_tables points to the left-most leaf.

    List of all base tables local to a subquery including all view
    tables. Unlike 'next_local', this in this list views are *not*
    leaves. Created in setup_tables() -> make_leaves_list().
  */
  /* 
    Subqueries that will need to be converted to semi-join nests, including
    those converted to jtbm nests. The list is emptied when conversion is done.
  */
  List<Item_in_subselect> sj_subselects;
  
  /*
    Needed to correctly generate 'PRIMARY' or 'SIMPLE' for select_type column
    of EXPLAIN
  */
  bool have_merged_subqueries;

  List<TABLE_LIST> leaf_tables;
  List<TABLE_LIST> leaf_tables_exec;
  List<TABLE_LIST> leaf_tables_prep;
  enum leaf_list_state {UNINIT, READY, SAVED};
  enum leaf_list_state prep_leaf_list_state;
  uint insert_tables;
  st_select_lex *merged_into; /* select which this select is merged into */
                              /* (not 0 only for views/derived tables)   */

  const char *type;               /* type of select for EXPLAIN          */

  SQL_I_List<ORDER> order_list;   /* ORDER clause */
  SQL_I_List<ORDER> gorder_list;
  Item *select_limit, *offset_limit;  /* LIMIT clause parameters */
  // Arrays of pointers to top elements of all_fields list
  Item **ref_pointer_array;
  size_t ref_pointer_array_size; // Number of elements in array.

  /*
    number of items in select_list and HAVING clause used to get number
    bigger then can be number of entries that will be added to all item
    list during split_sum_func
  */
  uint select_n_having_items;
  uint cond_count;    /* number of sargable Items in where/having/on          */
  uint between_count; /* number of between predicates in where/having/on      */
  uint max_equal_elems; /* maximal number of elements in multiple equalities  */   
  /*
    Number of fields used in select list or where clause of current select
    and all inner subselects.
  */
  uint select_n_where_fields;
  /* reserved for exists 2 in */
  uint select_n_reserved;
  enum_parsing_place parsing_place; /* where we are parsing expression */
  bool with_sum_func;   /* sum function indicator */

  ulong table_join_options;
  uint in_sum_expr;
  uint select_number; /* number of select (used for EXPLAIN) */

  /*
    nest_levels are local to the query or VIEW,
    and that view merge procedure does not re-calculate them.
    So we also have to remember unit against which we count levels.
  */
  SELECT_LEX_UNIT *nest_level_base;
  int nest_level;     /* nesting level of select */
  Item_sum *inner_sum_func_list; /* list of sum func in nested selects */ 
  uint with_wild; /* item list contain '*' */
  bool  braces;   	/* SELECT ... UNION (SELECT ... ) <- this braces */
  /* TRUE when having fix field called in processing of this SELECT */
  bool having_fix_field;
  /* List of references to fields referenced from inner selects */
  List<Item_outer_ref> inner_refs_list;
  /* Number of Item_sum-derived objects in this SELECT */
  uint n_sum_items;
  /* Number of Item_sum-derived objects in children and descendant SELECTs */
  uint n_child_sum_items;

  /* explicit LIMIT clause was used */
  bool explicit_limit;
  /*
    This array is used to note  whether we have any candidates for
    expression caching in the corresponding clauses
  */
  bool expr_cache_may_be_used[PARSING_PLACE_SIZE];
  /*
    there are subquery in HAVING clause => we can't close tables before
    query processing end even if we use temporary table
  */
  bool subquery_in_having;
  /* TRUE <=> this SELECT is correlated w.r.t. some ancestor select */
  bool is_correlated;
  /*
    This variable is required to ensure proper work of subqueries and
    stored procedures. Generally, one should use the states of
    Query_arena to determine if it's a statement prepare or first
    execution of a stored procedure. However, in case when there was an
    error during the first execution of a stored procedure, the SP body
    is not expelled from the SP cache. Therefore, a deeply nested
    subquery might be left unoptimized. So we need this per-subquery
    variable to inidicate the optimization/execution state of every
    subquery. Prepared statements work OK in that regard, as in
    case of an error during prepare the PS is not created.
  */
  bool first_execution;
  bool first_natural_join_processing;
  bool first_cond_optimization;
  /* do not wrap view fields with Item_ref */
  bool no_wrap_view_item;
  /* exclude this select from check of unique_table() */
  bool exclude_from_table_unique_test;
  /* List of fields that aren't under an aggregate function */
  List<Item_field> non_agg_fields;
  /* index in the select list of the expression currently being fixed */
  int cur_pos_in_select_list;

  List<udf_func>     udf_list;                  /* udf function calls stack */

  /* 
    This is a copy of the original JOIN USING list that comes from
    the parser. The parser :
      1. Sets the natural_join of the second TABLE_LIST in the join
         and the st_select_lex::prev_join_using.
      2. Makes a parent TABLE_LIST and sets its is_natural_join/
       join_using_fields members.
      3. Uses the wrapper TABLE_LIST as a table in the upper level.
    We cannot assign directly to join_using_fields in the parser because
    at stage (1.) the parent TABLE_LIST is not constructed yet and
    the assignment will override the JOIN USING fields of the lower level
    joins on the right.
  */
  List<String> *prev_join_using;

  /* namp of nesting SELECT visibility (for aggregate functions check) */
  nesting_map name_visibility_map;

  void init_query();
  void init_select();
  st_select_lex_unit* master_unit() { return (st_select_lex_unit*) master; }
  st_select_lex_unit* first_inner_unit() 
  { 
    return (st_select_lex_unit*) slave; 
  }
  st_select_lex* outer_select();
  st_select_lex* next_select() { return (st_select_lex*) next; }
  st_select_lex* next_select_in_list() 
  {
    return (st_select_lex*) link_next;
  }
  st_select_lex_node** next_select_in_list_addr()
  {
    return &link_next;
  }
  st_select_lex* return_after_parsing()
  {
    return master_unit()->return_after_parsing();
  }
  inline bool is_subquery_function() { return master_unit()->item != 0; }

  bool mark_as_dependent(THD *thd, st_select_lex *last, Item *dependency);

  bool set_braces(bool value);
  bool inc_in_sum_expr();
  uint get_in_sum_expr();

  bool add_item_to_list(THD *thd, Item *item);
  bool add_group_to_list(THD *thd, Item *item, bool asc);
  bool add_ftfunc_to_list(THD *thd, Item_func_match *func);
  bool add_order_to_list(THD *thd, Item *item, bool asc);
  bool add_gorder_to_list(THD *thd, Item *item, bool asc);
  TABLE_LIST* add_table_to_list(THD *thd, Table_ident *table,
				LEX_STRING *alias,
				ulong table_options,
				thr_lock_type flags= TL_UNLOCK,
                                enum_mdl_type mdl_type= MDL_SHARED_READ,
				List<Index_hint> *hints= 0,
                                List<String> *partition_names= 0,
                                LEX_STRING *option= 0);
  TABLE_LIST* get_table_list();
  bool init_nested_join(THD *thd);
  TABLE_LIST *end_nested_join(THD *thd);
  TABLE_LIST *nest_last_join(THD *thd);
  void add_joined_table(TABLE_LIST *table);
  TABLE_LIST *convert_right_join();
  List<Item>* get_item_list();
  ulong get_table_join_options();
  void set_lock_for_tables(thr_lock_type lock_type);
  inline void init_order()
  {
    order_list.elements= 0;
    order_list.first= 0;
    order_list.next= &order_list.first;
  }
  /*
    This method created for reiniting LEX in mysql_admin_table() and can be
    used only if you are going remove all SELECT_LEX & units except belonger
    to LEX (LEX::unit & LEX::select, for other purposes there are
    SELECT_LEX_UNIT::exclude_level & SELECT_LEX_UNIT::exclude_tree
  */
  void cut_subtree() { slave= 0; }
  bool test_limit();
  /**
    Get offset for LIMIT.

    Evaluate offset item if necessary.

    @return Number of rows to skip.
  */
  ha_rows get_offset();
  /**
   Get limit.

   Evaluate limit item if necessary.

   @return Limit of rows in result.
  */
  ha_rows get_limit();

  friend void lex_start(THD *thd);
  st_select_lex() : group_list_ptrs(NULL), braces(0),
  n_sum_items(0), n_child_sum_items(0)
  {}
  void make_empty_select()
  {
    init_query();
    init_select();
  }
  bool setup_ref_array(THD *thd, uint order_group_num);
  void print(THD *thd, String *str, enum_query_type query_type);
  static void print_order(String *str,
                          ORDER *order,
                          enum_query_type query_type);
  void print_limit(THD *thd, String *str, enum_query_type query_type);
  void fix_prepare_information(THD *thd, Item **conds, Item **having_conds);
  /*
    Destroy the used execution plan (JOIN) of this subtree (this
    SELECT_LEX and all nested SELECT_LEXes and SELECT_LEX_UNITs).
  */
  bool cleanup();
  /*
    Recursively cleanup the join of this select lex and of all nested
    select lexes.
  */
  void cleanup_all_joins(bool full);

  void set_index_hint_type(enum index_hint_type type, index_clause_map clause);

  /* 
   Add a index hint to the tagged list of hints. The type and clause of the
   hint will be the current ones (set by set_index_hint()) 
  */
  bool add_index_hint (THD *thd, char *str, uint length);

  /* make a list to hold index hints */
  void alloc_index_hints (THD *thd);
  /* read and clear the index hints */
  List<Index_hint>* pop_index_hints(void) 
  {
    List<Index_hint> *hints= index_hints;
    index_hints= NULL;
    return hints;
  }

  void clear_index_hints(void) { index_hints= NULL; }
  bool is_part_of_union() { return master_unit()->is_union(); }
  bool is_top_level_node() 
  { 
    return (select_number == 1) && !is_part_of_union();
  }
  bool optimize_unflattened_subqueries(bool const_only);
  /* Set the EXPLAIN type for this subquery. */
  void set_explain_type(bool on_the_fly);
  bool handle_derived(LEX *lex, uint phases);
  void append_table_to_list(TABLE_LIST *TABLE_LIST::*link, TABLE_LIST *table);
  bool get_free_table_map(table_map *map, uint *tablenr);
  void replace_leaf_table(TABLE_LIST *table, List<TABLE_LIST> &tbl_list);
  void remap_tables(TABLE_LIST *derived, table_map map,
                    uint tablenr, st_select_lex *parent_lex);
  bool merge_subquery(THD *thd, TABLE_LIST *derived, st_select_lex *subq_lex,
                      uint tablenr, table_map map);
  inline bool is_mergeable()
  {
    return (next_select() == 0 && group_list.elements == 0 &&
            having == 0 && with_sum_func == 0 &&
            table_list.elements >= 1 && !(options & SELECT_DISTINCT) &&
            select_limit == 0);
  }
  void mark_as_belong_to_derived(TABLE_LIST *derived);
  void increase_derived_records(ha_rows records);
  void update_used_tables();
  void update_correlated_cache();
  void mark_const_derived(bool empty);

  bool save_leaf_tables(THD *thd);
  bool save_prep_leaf_tables(THD *thd);

  bool is_merged_child_of(st_select_lex *ancestor);

  /*
    For MODE_ONLY_FULL_GROUP_BY we need to maintain two flags:
     - Non-aggregated fields are used in this select.
     - Aggregate functions are used in this select.
    In MODE_ONLY_FULL_GROUP_BY only one of these may be true.
  */
  bool non_agg_field_used() const { return m_non_agg_field_used; }
  bool agg_func_used()      const { return m_agg_func_used; }

  void set_non_agg_field_used(bool val) { m_non_agg_field_used= val; }
  void set_agg_func_used(bool val)      { m_agg_func_used= val; }

private:
  bool m_non_agg_field_used;
  bool m_agg_func_used;

  /* current index hint kind. used in filling up index_hints */
  enum index_hint_type current_index_hint_type;
  index_clause_map current_index_hint_clause;
  /* a list of USE/FORCE/IGNORE INDEX */
  List<Index_hint> *index_hints;
};
typedef class st_select_lex SELECT_LEX;

inline bool st_select_lex_unit::is_union ()
{ 
  return first_select()->next_select() && 
    first_select()->next_select()->linkage == UNION_TYPE;
}


struct st_sp_chistics
{
  LEX_STRING comment;
  enum enum_sp_suid_behaviour suid;
  bool detistic;
  enum enum_sp_data_access daccess;
};

struct st_trg_chistics
{
  enum trg_action_time_type action_time;
  enum trg_event_type event;
};

extern sys_var *trg_new_row_fake_var;

enum xa_option_words {XA_NONE, XA_JOIN, XA_RESUME, XA_ONE_PHASE,
                      XA_SUSPEND, XA_FOR_MIGRATE};

class Sroutine_hash_entry;

/*
  Class representing list of all tables used by statement and other
  information which is necessary for opening and locking its tables,
  like SQL command for this statement.

  Also contains information about stored functions used by statement
  since during its execution we may have to add all tables used by its
  stored functions/triggers to this list in order to pre-open and lock
  them.

  Also used by LEX::reset_n_backup/restore_backup_query_tables_list()
  methods to save and restore this information.
*/

class Query_tables_list
{
public:
  /**
    SQL command for this statement. Part of this class since the
    process of opening and locking tables for the statement needs
    this information to determine correct type of lock for some of
    the tables.
  */
  enum_sql_command sql_command;
  /* Global list of all tables used by this statement */
  TABLE_LIST *query_tables;
  /* Pointer to next_global member of last element in the previous list. */
  TABLE_LIST **query_tables_last;
  /*
    If non-0 then indicates that query requires prelocking and points to
    next_global member of last own element in query table list (i.e. last
    table which was not added to it as part of preparation to prelocking).
    0 - indicates that this query does not need prelocking.
  */
  TABLE_LIST **query_tables_own_last;
  /*
    Set of stored routines called by statement.
    (Note that we use lazy-initialization for this hash).
  */
  enum { START_SROUTINES_HASH_SIZE= 16 };
  HASH sroutines;
  /*
    List linking elements of 'sroutines' set. Allows you to add new elements
    to this set as you iterate through the list of existing elements.
    'sroutines_list_own_last' is pointer to ::next member of last element of
    this list which represents routine which is explicitly used by query.
    'sroutines_list_own_elements' number of explicitly used routines.
    We use these two members for restoring of 'sroutines_list' to the state
    in which it was right after query parsing.
  */
  SQL_I_List<Sroutine_hash_entry> sroutines_list;
  Sroutine_hash_entry **sroutines_list_own_last;
  uint sroutines_list_own_elements;

  /**
    Locking state of tables in this particular statement.

    If we under LOCK TABLES or in prelocked mode we consider tables
    for the statement to be "locked" if there was a call to lock_tables()
    (which called handler::start_stmt()) for tables of this statement
    and there was no matching close_thread_tables() call.

    As result this state may differ significantly from one represented
    by Open_tables_state::lock/locked_tables_mode more, which are always
    "on" under LOCK TABLES or in prelocked mode.
  */
  enum enum_lock_tables_state {
    LTS_NOT_LOCKED = 0,
    LTS_LOCKED
  };
  enum_lock_tables_state lock_tables_state;
  bool is_query_tables_locked()
  {
    return (lock_tables_state == LTS_LOCKED);
  }

  /**
    Number of tables which were open by open_tables() and to be locked
    by lock_tables().
    Note that we set this member only in some cases, when this value
    needs to be passed from open_tables() to lock_tables() which are
    separated by some amount of code.
  */
  uint table_count;

   /*
    These constructor and destructor serve for creation/destruction
    of Query_tables_list instances which are used as backup storage.
  */
  Query_tables_list() {}
  ~Query_tables_list() {}

  /* Initializes (or resets) Query_tables_list object for "real" use. */
  void reset_query_tables_list(bool init);
  void destroy_query_tables_list();
  void set_query_tables_list(Query_tables_list *state)
  {
    *this= *state;
  }

  /*
    Direct addition to the list of query tables.
    If you are using this function, you must ensure that the table
    object, in particular table->db member, is initialized.
  */
  void add_to_query_tables(TABLE_LIST *table)
  {
    *(table->prev_global= query_tables_last)= table;
    query_tables_last= &table->next_global;
  }
  bool requires_prelocking()
  {
    return MY_TEST(query_tables_own_last);
  }
  void mark_as_requiring_prelocking(TABLE_LIST **tables_own_last)
  {
    query_tables_own_last= tables_own_last;
  }
  /* Return pointer to first not-own table in query-tables or 0 */
  TABLE_LIST* first_not_own_table()
  {
    return ( query_tables_own_last ? *query_tables_own_last : 0);
  }
  void chop_off_not_own_tables()
  {
    if (query_tables_own_last)
    {
      *query_tables_own_last= 0;
      query_tables_last= query_tables_own_last;
      query_tables_own_last= 0;
    }
  }

  /** Return a pointer to the last element in query table list. */
  TABLE_LIST *last_table()
  {
    /* Don't use offsetof() macro in order to avoid warnings. */
    return query_tables ?
           (TABLE_LIST*) ((char*) query_tables_last -
                          ((char*) &(query_tables->next_global) -
                           (char*) query_tables)) :
           0;
  }

  /**
    Enumeration listing of all types of unsafe statement.

    @note The order of elements of this enumeration type must
    correspond to the order of the elements of the @c explanations
    array defined in the body of @c THD::issue_unsafe_warnings.
  */
  enum enum_binlog_stmt_unsafe {
    /**
      SELECT..LIMIT is unsafe because the set of rows returned cannot
      be predicted.
    */
    BINLOG_STMT_UNSAFE_LIMIT= 0,
    /**
      INSERT DELAYED is unsafe because the time when rows are inserted
      cannot be predicted.
    */
    BINLOG_STMT_UNSAFE_INSERT_DELAYED,
    /**
      Access to log tables is unsafe because slave and master probably
      log different things.
    */
    BINLOG_STMT_UNSAFE_SYSTEM_TABLE,
    /**
      Inserting into an autoincrement column in a stored routine is unsafe.
      Even with just one autoincrement column, if the routine is invoked more than 
      once slave is not guaranteed to execute the statement graph same way as 
      the master.
      And since it's impossible to estimate how many times a routine can be invoked at 
      the query pre-execution phase (see lock_tables), the statement is marked
      pessimistically unsafe. 
    */
    BINLOG_STMT_UNSAFE_AUTOINC_COLUMNS,
    /**
      Using a UDF (user-defined function) is unsafe.
    */
    BINLOG_STMT_UNSAFE_UDF,
    /**
      Using most system variables is unsafe, because slave may run
      with different options than master.
    */
    BINLOG_STMT_UNSAFE_SYSTEM_VARIABLE,
    /**
      Using some functions is unsafe (e.g., UUID).
    */
    BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION,

    /**
      Mixing transactional and non-transactional statements are unsafe if
      non-transactional reads or writes are occur after transactional
      reads or writes inside a transaction.
    */
    BINLOG_STMT_UNSAFE_NONTRANS_AFTER_TRANS,

    /**
      Mixing self-logging and non-self-logging engines in a statement
      is unsafe.
    */
    BINLOG_STMT_UNSAFE_MULTIPLE_ENGINES_AND_SELF_LOGGING_ENGINE,

    /**
      Statements that read from both transactional and non-transactional
      tables and write to any of them are unsafe.
    */
    BINLOG_STMT_UNSAFE_MIXED_STATEMENT,

    /**
      INSERT...IGNORE SELECT is unsafe because which rows are ignored depends
      on the order that rows are retrieved by SELECT. This order cannot be
      predicted and may differ on master and the slave.
    */
    BINLOG_STMT_UNSAFE_INSERT_IGNORE_SELECT,

    /**
      INSERT...SELECT...UPDATE is unsafe because which rows are updated depends
      on the order that rows are retrieved by SELECT. This order cannot be
      predicted and may differ on master and the slave.
    */
    BINLOG_STMT_UNSAFE_INSERT_SELECT_UPDATE,

    /**
     Query that writes to a table with auto_inc column after selecting from 
     other tables are unsafe as the order in which the rows are retrieved by
     select may differ on master and slave.
    */
    BINLOG_STMT_UNSAFE_WRITE_AUTOINC_SELECT,

    /**
      INSERT...REPLACE SELECT is unsafe because which rows are replaced depends
      on the order that rows are retrieved by SELECT. This order cannot be
      predicted and may differ on master and the slave.
    */
    BINLOG_STMT_UNSAFE_REPLACE_SELECT,

    /**
      CREATE TABLE... IGNORE... SELECT is unsafe because which rows are ignored
      depends on the order that rows are retrieved by SELECT. This order cannot
      be predicted and may differ on master and the slave.
    */
    BINLOG_STMT_UNSAFE_CREATE_IGNORE_SELECT,

    /**
      CREATE TABLE...REPLACE... SELECT is unsafe because which rows are replaced
      depends on the order that rows are retrieved from SELECT. This order
      cannot be predicted and may differ on master and the slave
    */
    BINLOG_STMT_UNSAFE_CREATE_REPLACE_SELECT,

    /**
      CREATE TABLE...SELECT on a table with auto-increment column is unsafe
      because which rows are replaced depends on the order that rows are
      retrieved from SELECT. This order cannot be predicted and may differ on
      master and the slave
    */
    BINLOG_STMT_UNSAFE_CREATE_SELECT_AUTOINC,

    /**
      UPDATE...IGNORE is unsafe because which rows are ignored depends on the
      order that rows are updated. This order cannot be predicted and may differ
      on master and the slave.
    */
    BINLOG_STMT_UNSAFE_UPDATE_IGNORE,

    /**
      INSERT... ON DUPLICATE KEY UPDATE on a table with more than one
      UNIQUE KEYS  is unsafe.
    */
    BINLOG_STMT_UNSAFE_INSERT_TWO_KEYS,

    /**
       INSERT into auto-inc field which is not the first part of composed
       primary key.
    */
    BINLOG_STMT_UNSAFE_AUTOINC_NOT_FIRST,

    /* The last element of this enumeration type. */
    BINLOG_STMT_UNSAFE_COUNT
  };
  /**
    This has all flags from 0 (inclusive) to BINLOG_STMT_FLAG_COUNT
    (exclusive) set.
  */
  static const int BINLOG_STMT_UNSAFE_ALL_FLAGS=
    ((1 << BINLOG_STMT_UNSAFE_COUNT) - 1);

  /**
    Maps elements of enum_binlog_stmt_unsafe to error codes.
  */
  static const int binlog_stmt_unsafe_errcode[BINLOG_STMT_UNSAFE_COUNT];

  /**
    Determine if this statement is marked as unsafe.

    @retval 0 if the statement is not marked as unsafe.
    @retval nonzero if the statement is marked as unsafe.
  */
  inline bool is_stmt_unsafe() const {
    return get_stmt_unsafe_flags() != 0;
  }

  /**
    Flag the current (top-level) statement as unsafe.
    The flag will be reset after the statement has finished.

    @param unsafe_type The type of unsafety: one of the @c
    BINLOG_STMT_FLAG_UNSAFE_* flags in @c enum_binlog_stmt_flag.
  */
  inline void set_stmt_unsafe(enum_binlog_stmt_unsafe unsafe_type) {
    DBUG_ENTER("set_stmt_unsafe");
    DBUG_ASSERT(unsafe_type >= 0 && unsafe_type < BINLOG_STMT_UNSAFE_COUNT);
    binlog_stmt_flags|= (1U << unsafe_type);
    DBUG_VOID_RETURN;
  }

  /**
    Set the bits of binlog_stmt_flags determining the type of
    unsafeness of the current statement.  No existing bits will be
    cleared, but new bits may be set.

    @param flags A binary combination of zero or more bits, (1<<flag)
    where flag is a member of enum_binlog_stmt_unsafe.
  */
  inline void set_stmt_unsafe_flags(uint32 flags) {
    DBUG_ENTER("set_stmt_unsafe_flags");
    DBUG_ASSERT((flags & ~BINLOG_STMT_UNSAFE_ALL_FLAGS) == 0);
    binlog_stmt_flags|= flags;
    DBUG_VOID_RETURN;
  }

  /**
    Return a binary combination of all unsafe warnings for the
    statement.  If the statement has been marked as unsafe by the
    'flag' member of enum_binlog_stmt_unsafe, then the return value
    from this function has bit (1<<flag) set to 1.
  */
  inline uint32 get_stmt_unsafe_flags() const {
    DBUG_ENTER("get_stmt_unsafe_flags");
    DBUG_RETURN(binlog_stmt_flags & BINLOG_STMT_UNSAFE_ALL_FLAGS);
  }

  /**
    Mark the current statement as safe; i.e., clear all bits in
    binlog_stmt_flags that correspond to elements of
    enum_binlog_stmt_unsafe.
  */
  inline void clear_stmt_unsafe() {
    DBUG_ENTER("clear_stmt_unsafe");
    binlog_stmt_flags&= ~BINLOG_STMT_UNSAFE_ALL_FLAGS;
    DBUG_VOID_RETURN;
  }

  /**
    Determine if this statement is a row injection.

    @retval 0 if the statement is not a row injection
    @retval nonzero if the statement is a row injection
  */
  inline bool is_stmt_row_injection() const {
    return binlog_stmt_flags &
      (1U << (BINLOG_STMT_UNSAFE_COUNT + BINLOG_STMT_TYPE_ROW_INJECTION));
  }

  /**
    Flag the statement as a row injection.  A row injection is either
    a BINLOG statement, or a row event in the relay log executed by
    the slave SQL thread.
  */
  inline void set_stmt_row_injection() {
    DBUG_ENTER("set_stmt_row_injection");
    binlog_stmt_flags|=
      (1U << (BINLOG_STMT_UNSAFE_COUNT + BINLOG_STMT_TYPE_ROW_INJECTION));
    DBUG_VOID_RETURN;
  }

  enum enum_stmt_accessed_table
  {
    /*
       If a transactional table is about to be read. Note that
       a write implies a read.
    */
    STMT_READS_TRANS_TABLE= 0,
    /*
       If a non-transactional table is about to be read. Note that
       a write implies a read.
    */
    STMT_READS_NON_TRANS_TABLE,
    /*
       If a temporary transactional table is about to be read. Note
       that a write implies a read.
    */
    STMT_READS_TEMP_TRANS_TABLE,
    /*
       If a temporary non-transactional table is about to be read. Note
      that a write implies a read.
    */
    STMT_READS_TEMP_NON_TRANS_TABLE,
    /*
       If a transactional table is about to be updated.
    */
    STMT_WRITES_TRANS_TABLE,
    /*
       If a non-transactional table is about to be updated.
    */
    STMT_WRITES_NON_TRANS_TABLE,
    /*
       If a temporary transactional table is about to be updated.
    */
    STMT_WRITES_TEMP_TRANS_TABLE,
    /*
       If a temporary non-transactional table is about to be updated.
    */
    STMT_WRITES_TEMP_NON_TRANS_TABLE,
    /*
      The last element of the enumeration. Please, if necessary add
      anything before this.
    */
    STMT_ACCESS_TABLE_COUNT
  };

#ifndef DBUG_OFF
  static inline const char *stmt_accessed_table_string(enum_stmt_accessed_table accessed_table)
  {
    switch (accessed_table)
    {
      case STMT_READS_TRANS_TABLE:
         return "STMT_READS_TRANS_TABLE";
      break;
      case STMT_READS_NON_TRANS_TABLE:
        return "STMT_READS_NON_TRANS_TABLE";
      break;
      case STMT_READS_TEMP_TRANS_TABLE:
        return "STMT_READS_TEMP_TRANS_TABLE";
      break;
      case STMT_READS_TEMP_NON_TRANS_TABLE:
        return "STMT_READS_TEMP_NON_TRANS_TABLE";
      break;  
      case STMT_WRITES_TRANS_TABLE:
        return "STMT_WRITES_TRANS_TABLE";
      break;
      case STMT_WRITES_NON_TRANS_TABLE:
        return "STMT_WRITES_NON_TRANS_TABLE";
      break;
      case STMT_WRITES_TEMP_TRANS_TABLE:
        return "STMT_WRITES_TEMP_TRANS_TABLE";
      break;
      case STMT_WRITES_TEMP_NON_TRANS_TABLE:
        return "STMT_WRITES_TEMP_NON_TRANS_TABLE";
      break;
      case STMT_ACCESS_TABLE_COUNT:
      default:
        DBUG_ASSERT(0);
      break;
    }
    MY_ASSERT_UNREACHABLE();
    return "";
  }
#endif  /* DBUG */
               
  #define BINLOG_DIRECT_ON 0xF0    /* unsafe when
                                      --binlog-direct-non-trans-updates
                                      is ON */

  #define BINLOG_DIRECT_OFF 0xF    /* unsafe when
                                      --binlog-direct-non-trans-updates
                                      is OFF */

  #define TRX_CACHE_EMPTY 0x33     /* unsafe when trx-cache is empty */

  #define TRX_CACHE_NOT_EMPTY 0xCC /* unsafe when trx-cache is not empty */

  #define IL_LT_REPEATABLE 0xAA    /* unsafe when < ISO_REPEATABLE_READ */

  #define IL_GTE_REPEATABLE 0x55   /* unsafe when >= ISO_REPEATABLE_READ */
  
  /**
    Sets the type of table that is about to be accessed while executing a
    statement.

    @param accessed_table Enumeration type that defines the type of table,
                           e.g. temporary, transactional, non-transactional.
  */
  inline void set_stmt_accessed_table(enum_stmt_accessed_table accessed_table)
  {
    DBUG_ENTER("LEX::set_stmt_accessed_table");

    DBUG_ASSERT(accessed_table >= 0 && accessed_table < STMT_ACCESS_TABLE_COUNT);
    stmt_accessed_table_flag |= (1U << accessed_table);

    DBUG_VOID_RETURN;
  }

  /**
    Checks if a type of table is about to be accessed while executing a
    statement.

    @param accessed_table Enumeration type that defines the type of table,
           e.g. temporary, transactional, non-transactional.

    @return
      @retval TRUE  if the type of the table is about to be accessed
      @retval FALSE otherwise
  */
  inline bool stmt_accessed_table(enum_stmt_accessed_table accessed_table)
  {
    DBUG_ENTER("LEX::stmt_accessed_table");

    DBUG_ASSERT(accessed_table >= 0 && accessed_table < STMT_ACCESS_TABLE_COUNT);

    DBUG_RETURN((stmt_accessed_table_flag & (1U << accessed_table)) != 0);
  }

  /**
    Checks if a temporary non-transactional table is about to be accessed
    while executing a statement.

    @return
      @retval TRUE  if a temporary non-transactional table is about to be
                    accessed
      @retval FALSE otherwise
  */
  inline bool stmt_accessed_non_trans_temp_table()
  {
    DBUG_ENTER("THD::stmt_accessed_non_trans_temp_table");

    DBUG_RETURN((stmt_accessed_table_flag &
                ((1U << STMT_READS_TEMP_NON_TRANS_TABLE) |
                 (1U << STMT_WRITES_TEMP_NON_TRANS_TABLE))) != 0);
  }

  /*
    Checks if a mixed statement is unsafe.

    
    @param in_multi_stmt_transaction_mode defines if there is an on-going
           multi-transactional statement.
    @param binlog_direct defines if --binlog-direct-non-trans-updates is
           active.
    @param trx_cache_is_not_empty defines if the trx-cache is empty or not.
    @param trx_isolation defines the isolation level.
 
    @return
      @retval TRUE if the mixed statement is unsafe
      @retval FALSE otherwise
  */
  inline bool is_mixed_stmt_unsafe(bool in_multi_stmt_transaction_mode,
                                   bool binlog_direct,
                                   bool trx_cache_is_not_empty,
                                   uint tx_isolation)
  {
    bool unsafe= FALSE;

    if (in_multi_stmt_transaction_mode)
    {
       uint condition=
         (binlog_direct ? BINLOG_DIRECT_ON : BINLOG_DIRECT_OFF) &
         (trx_cache_is_not_empty ? TRX_CACHE_NOT_EMPTY : TRX_CACHE_EMPTY) &
         (tx_isolation >= ISO_REPEATABLE_READ ? IL_GTE_REPEATABLE : IL_LT_REPEATABLE);

      unsafe= (binlog_unsafe_map[stmt_accessed_table_flag] & condition);

#if !defined(DBUG_OFF)
      DBUG_PRINT("LEX::is_mixed_stmt_unsafe", ("RESULT %02X %02X %02X\n", condition,
              binlog_unsafe_map[stmt_accessed_table_flag],
              (binlog_unsafe_map[stmt_accessed_table_flag] & condition)));
 
      int type_in= 0;
      for (; type_in < STMT_ACCESS_TABLE_COUNT; type_in++)
      {
        if (stmt_accessed_table((enum_stmt_accessed_table) type_in))
          DBUG_PRINT("LEX::is_mixed_stmt_unsafe", ("ACCESSED %s ",
                  stmt_accessed_table_string((enum_stmt_accessed_table) type_in)));
      }
#endif
    }

    if (stmt_accessed_table(STMT_WRITES_NON_TRANS_TABLE) &&
      stmt_accessed_table(STMT_READS_TRANS_TABLE) &&
      tx_isolation < ISO_REPEATABLE_READ)
      unsafe= TRUE;
    else if (stmt_accessed_table(STMT_WRITES_TEMP_NON_TRANS_TABLE) &&
      stmt_accessed_table(STMT_READS_TRANS_TABLE) &&
      tx_isolation < ISO_REPEATABLE_READ)
      unsafe= TRUE;

    return(unsafe);
  }

  /**
    true if the parsed tree contains references to stored procedures
    or functions, false otherwise
  */
  bool uses_stored_routines() const
  { return sroutines_list.elements != 0; }

private:

  /**
    Enumeration listing special types of statements.

    Currently, the only possible type is ROW_INJECTION.
  */
  enum enum_binlog_stmt_type {
    /**
      The statement is a row injection (i.e., either a BINLOG
      statement or a row event executed by the slave SQL thread).
    */
    BINLOG_STMT_TYPE_ROW_INJECTION = 0,

    /** The last element of this enumeration type. */
    BINLOG_STMT_TYPE_COUNT
  };

  /**
    Bit field indicating the type of statement.

    There are two groups of bits:

    - The low BINLOG_STMT_UNSAFE_COUNT bits indicate the types of
      unsafeness that the current statement has.

    - The next BINLOG_STMT_TYPE_COUNT bits indicate if the statement
      is of some special type.

    This must be a member of LEX, not of THD: each stored procedure
    needs to remember its unsafeness state between calls and each
    stored procedure has its own LEX object (but no own THD object).
  */
  uint32 binlog_stmt_flags;

  /**
    Bit field that determines the type of tables that are about to be
    be accessed while executing a statement.
  */
  uint32 stmt_accessed_table_flag;
};


/*
  st_parsing_options contains the flags for constructions that are
  allowed in the current statement.
*/

struct st_parsing_options
{
  bool allows_variable;
  bool allows_select_into;
  bool allows_select_procedure;
  bool allows_derived;

  st_parsing_options() { reset(); }
  void reset();
};


/**
  The state of the lexical parser, when parsing comments.
*/
enum enum_comment_state
{
  /**
    Not parsing comments.
  */
  NO_COMMENT,
  /**
    Parsing comments that need to be preserved.
    Typically, these are user comments '/' '*' ... '*' '/'.
  */
  PRESERVE_COMMENT,
  /**
    Parsing comments that need to be discarded.
    Typically, these are special comments '/' '*' '!' ... '*' '/',
    or '/' '*' '!' 'M' 'M' 'm' 'm' 'm' ... '*' '/', where the comment
    markers should not be expanded.
  */
  DISCARD_COMMENT
};


/**
  @brief This class represents the character input stream consumed during
  lexical analysis.

  In addition to consuming the input stream, this class performs some
  comment pre processing, by filtering out out of bound special text
  from the query input stream.
  Two buffers, with pointers inside each buffers, are maintained in
  parallel. The 'raw' buffer is the original query text, which may
  contain out-of-bound comments. The 'cpp' (for comments pre processor)
  is the pre-processed buffer that contains only the query text that
  should be seen once out-of-bound data is removed.
*/

class Lex_input_stream
{
  size_t unescape(CHARSET_INFO *cs, char *to,
                  const char *str, const char *end, int sep);
public:
  Lex_input_stream()
  {
  }

  ~Lex_input_stream()
  {
  }

  /**
     Object initializer. Must be called before usage.

     @retval FALSE OK
     @retval TRUE  Error
  */
  bool init(THD *thd, char *buff, unsigned int length);

  void reset(char *buff, unsigned int length);

  /**
    Set the echo mode.

    When echo is true, characters parsed from the raw input stream are
    preserved. When false, characters parsed are silently ignored.
    @param echo the echo mode.
  */
  void set_echo(bool echo)
  {
    m_echo= echo;
  }

  void save_in_comment_state()
  {
    m_echo_saved= m_echo;
    in_comment_saved= in_comment;
  }

  void restore_in_comment_state()
  {
    m_echo= m_echo_saved;
    in_comment= in_comment_saved;
  }

  /**
    Skip binary from the input stream.
    @param n number of bytes to accept.
  */
  void skip_binary(int n)
  {
    if (m_echo)
    {
      memcpy(m_cpp_ptr, m_ptr, n);
      m_cpp_ptr += n;
    }
    m_ptr += n;
  }

  /**
    Get a character, and advance in the stream.
    @return the next character to parse.
  */
  unsigned char yyGet()
  {
    char c= *m_ptr++;
    if (m_echo)
      *m_cpp_ptr++ = c;
    return c;
  }

  /**
    Get the last character accepted.
    @return the last character accepted.
  */
  unsigned char yyGetLast()
  {
    return m_ptr[-1];
  }

  /**
    Look at the next character to parse, but do not accept it.
  */
  unsigned char yyPeek()
  {
    return m_ptr[0];
  }

  /**
    Look ahead at some character to parse.
    @param n offset of the character to look up
  */
  unsigned char yyPeekn(int n)
  {
    return m_ptr[n];
  }

  /**
    Cancel the effect of the last yyGet() or yySkip().
    Note that the echo mode should not change between calls to yyGet / yySkip
    and yyUnget. The caller is responsible for ensuring that.
  */
  void yyUnget()
  {
    m_ptr--;
    if (m_echo)
      m_cpp_ptr--;
  }

  /**
    Accept a character, by advancing the input stream.
  */
  void yySkip()
  {
    if (m_echo)
      *m_cpp_ptr++ = *m_ptr++;
    else
      m_ptr++;
  }

  /**
    Accept multiple characters at once.
    @param n the number of characters to accept.
  */
  void yySkipn(int n)
  {
    if (m_echo)
    {
      memcpy(m_cpp_ptr, m_ptr, n);
      m_cpp_ptr += n;
    }
    m_ptr += n;
  }

  /**
    Puts a character back into the stream, canceling
    the effect of the last yyGet() or yySkip().
    Note that the echo mode should not change between calls
    to unput, get, or skip from the stream.
  */
  char *yyUnput(char ch)
  {
    *--m_ptr= ch;
    if (m_echo)
      m_cpp_ptr--;
    return m_ptr;
  }

  /**
    End of file indicator for the query text to parse.
    @return true if there are no more characters to parse
  */
  bool eof()
  {
    return (m_ptr >= m_end_of_query);
  }

  /**
    End of file indicator for the query text to parse.
    @param n number of characters expected
    @return true if there are less than n characters to parse
  */
  bool eof(int n)
  {
    return ((m_ptr + n) >= m_end_of_query);
  }

  /** Get the raw query buffer. */
  const char *get_buf()
  {
    return m_buf;
  }

  /** Get the pre-processed query buffer. */
  const char *get_cpp_buf()
  {
    return m_cpp_buf;
  }

  /** Get the end of the raw query buffer. */
  const char *get_end_of_query()
  {
    return m_end_of_query;
  }

  /** Mark the stream position as the start of a new token. */
  void start_token()
  {
    m_tok_start_prev= m_tok_start;
    m_tok_start= m_ptr;
    m_tok_end= m_ptr;

    m_cpp_tok_start_prev= m_cpp_tok_start;
    m_cpp_tok_start= m_cpp_ptr;
    m_cpp_tok_end= m_cpp_ptr;
  }

  /**
    Adjust the starting position of the current token.
    This is used to compensate for starting whitespace.
  */
  void restart_token()
  {
    m_tok_start= m_ptr;
    m_cpp_tok_start= m_cpp_ptr;
  }

  /** Get the token start position, in the raw buffer. */
  const char *get_tok_start()
  {
    return m_tok_start;
  }

  /** Get the token start position, in the pre-processed buffer. */
  const char *get_cpp_tok_start()
  {
    return m_cpp_tok_start;
  }

  /** Get the token end position, in the raw buffer. */
  const char *get_tok_end()
  {
    return m_tok_end;
  }

  /** Get the token end position, in the pre-processed buffer. */
  const char *get_cpp_tok_end()
  {
    return m_cpp_tok_end;
  }

  /** Get the previous token start position, in the raw buffer. */
  const char *get_tok_start_prev()
  {
    return m_tok_start_prev;
  }

  /** Get the current stream pointer, in the raw buffer. */
  const char *get_ptr()
  {
    return m_ptr;
  }

  /** Get the current stream pointer, in the pre-processed buffer. */
  const char *get_cpp_ptr()
  {
    return m_cpp_ptr;
  }

  /** Get the length of the current token, in the raw buffer. */
  uint yyLength()
  {
    /*
      The assumption is that the lexical analyser is always 1 character ahead,
      which the -1 account for.
    */
    DBUG_ASSERT(m_ptr > m_tok_start);
    return (uint) ((m_ptr - m_tok_start) - 1);
  }

  /** Get the utf8-body string. */
  const char *get_body_utf8_str()
  {
    return m_body_utf8;
  }

  /** Get the utf8-body length. */
  uint get_body_utf8_length()
  {
    return (uint) (m_body_utf8_ptr - m_body_utf8);
  }

  void body_utf8_start(THD *thd, const char *begin_ptr);
  void body_utf8_append(const char *ptr);
  void body_utf8_append(const char *ptr, const char *end_ptr);
  void body_utf8_append_literal(THD *thd,
                                const LEX_STRING *txt,
                                CHARSET_INFO *txt_cs,
                                const char *end_ptr);

  /** Current thread. */
  THD *m_thd;

  /** Current line number. */
  uint yylineno;

  /** Interface with bison, value of the last token parsed. */
  LEX_YYSTYPE yylval;

  /**
    LALR(2) resolution, look ahead token.
    Value of the next token to return, if any,
    or -1, if no token was parsed in advance.
    Note: 0 is a legal token, and represents YYEOF.
  */
  int lookahead_token;

  /** LALR(2) resolution, value of the look ahead token.*/
  LEX_YYSTYPE lookahead_yylval;

  bool get_text(LEX_STRING *to, int pre_skip, int post_skip);

  void add_digest_token(uint token, LEX_YYSTYPE yylval);

  void reduce_digest_token(uint token_left, uint token_right);

private:
  /** Pointer to the current position in the raw input stream. */
  char *m_ptr;

  /** Starting position of the last token parsed, in the raw buffer. */
  const char *m_tok_start;

  /** Ending position of the previous token parsed, in the raw buffer. */
  const char *m_tok_end;

  /** End of the query text in the input stream, in the raw buffer. */
  const char *m_end_of_query;

  /** Starting position of the previous token parsed, in the raw buffer. */
  const char *m_tok_start_prev;

  /** Begining of the query text in the input stream, in the raw buffer. */
  const char *m_buf;

  /** Length of the raw buffer. */
  uint m_buf_length;

  /** Echo the parsed stream to the pre-processed buffer. */
  bool m_echo;
  bool m_echo_saved;

  /** Pre-processed buffer. */
  char *m_cpp_buf;

  /** Pointer to the current position in the pre-processed input stream. */
  char *m_cpp_ptr;

  /**
    Starting position of the last token parsed,
    in the pre-processed buffer.
  */
  const char *m_cpp_tok_start;

  /**
    Starting position of the previous token parsed,
    in the pre-procedded buffer.
  */
  const char *m_cpp_tok_start_prev;

  /**
    Ending position of the previous token parsed,
    in the pre-processed buffer.
  */
  const char *m_cpp_tok_end;

  /** UTF8-body buffer created during parsing. */
  char *m_body_utf8;

  /** Pointer to the current position in the UTF8-body buffer. */
  char *m_body_utf8_ptr;

  /**
    Position in the pre-processed buffer. The query from m_cpp_buf to
    m_cpp_utf_processed_ptr is converted to UTF8-body.
  */
  const char *m_cpp_utf8_processed_ptr;

public:

  /** Current state of the lexical analyser. */
  enum my_lex_states next_state;

  /**
    Position of ';' in the stream, to delimit multiple queries.
    This delimiter is in the raw buffer.
  */
  const char *found_semicolon;

  /** Token character bitmaps, to detect 7bit strings. */
  uchar tok_bitmap;

  /** SQL_MODE = IGNORE_SPACE. */
  bool ignore_space;

  /**
    TRUE if we're parsing a prepared statement: in this mode
    we should allow placeholders.
  */
  bool stmt_prepare_mode;
  /**
    TRUE if we should allow multi-statements.
  */
  bool multi_statements;

  /** State of the lexical analyser for comments. */
  enum_comment_state in_comment;
  enum_comment_state in_comment_saved;

  /**
    Starting position of the TEXT_STRING or IDENT in the pre-processed
    buffer.

    NOTE: this member must be used within MYSQLlex() function only.
  */
  const char *m_cpp_text_start;

  /**
    Ending position of the TEXT_STRING or IDENT in the pre-processed
    buffer.

    NOTE: this member must be used within MYSQLlex() function only.
    */
  const char *m_cpp_text_end;

  /**
    Character set specified by the character-set-introducer.

    NOTE: this member must be used within MYSQLlex() function only.
  */
  CHARSET_INFO *m_underscore_cs;

  /**
    Current statement digest instrumentation. 
  */
  sql_digest_state* m_digest;
};

/**
  Abstract representation of a statement.
  This class is an interface between the parser and the runtime.
  The parser builds the appropriate sub classes of Sql_statement
  to represent a SQL statement in the parsed tree.
  The execute() method in the sub classes contain the runtime implementation.
  Note that this interface is used for SQL statement recently implemented,
  the code for older statements tend to load the LEX structure with more
  attributes instead.
  The recommended way to implement new statements is to sub-class
  Sql_statement, as this improves code modularity (see the 'big switch' in
  dispatch_command()), and decrease the total size of the LEX structure
  (therefore saving memory in stored programs).
*/
class Sql_statement : public Sql_alloc
{
public:
  /**
    Execute this SQL statement.
    @param thd the current thread.
    @return 0 on success.
  */
  virtual bool execute(THD *thd) = 0;

protected:
  /**
    Constructor.
    @param lex the LEX structure that represents parts of this statement.
  */
  Sql_statement(LEX *lex)
    : m_lex(lex)
  {}

  /** Destructor. */
  virtual ~Sql_statement()
  {
    /*
      Sql_statement objects are allocated in thd->mem_root.
      In MySQL, the C++ destructor is never called, the underlying MEM_ROOT is
      simply destroyed instead.
      Do not rely on the destructor for any cleanup.
    */
    DBUG_ASSERT(FALSE);
  }

protected:
  /**
    The legacy LEX structure for this statement.
    The LEX structure contains the existing properties of the parsed tree.
    TODO: with time, attributes from LEX should move to sub classes of
    Sql_statement, so that the parser only builds Sql_statement objects
    with the minimum set of attributes, instead of a LEX structure that
    contains the collection of every possible attribute.
  */
  LEX *m_lex;
};


class Delete_plan;
class SQL_SELECT;

class Explain_query;
class Explain_update;
class Explain_delete;

/* 
  Query plan of a single-table UPDATE.
  (This is actually a plan for single-table DELETE also)
*/

class Update_plan
{
protected:
  bool impossible_where;
  bool no_partitions;
public:
  /*
    When single-table UPDATE updates a VIEW, that VIEW's select is still
    listed as the first child.  When we print EXPLAIN, it looks like a
    subquery.
    In order to get rid of it, updating_a_view=TRUE means that first child
    select should not be shown when printing EXPLAIN.
  */
  bool updating_a_view;
   
  /* Allocate things there */
  MEM_ROOT *mem_root;

  TABLE *table;
  SQL_SELECT *select;
  uint index;
  ha_rows scanned_rows;
  /*
    Top-level select_lex. Most of its fields are not used, we need it only to
    get to the subqueries.
  */
  SELECT_LEX *select_lex;
  
  key_map possible_keys;
  bool using_filesort;
  bool using_io_buffer;
  
  /* Set this plan to be a plan to do nothing because of impossible WHERE */
  void set_impossible_where() { impossible_where= true; }
  void set_no_partitions() { no_partitions= true; }

  Explain_update* save_explain_update_data(MEM_ROOT *mem_root, THD *thd);
protected:
  void save_explain_data_intern(MEM_ROOT *mem_root, Explain_update *eu, bool is_analyze);
public:
  virtual ~Update_plan() {}

  Update_plan(MEM_ROOT *mem_root_arg) : 
    impossible_where(false), no_partitions(false), 
    mem_root(mem_root_arg), 
    using_filesort(false), using_io_buffer(false)
  {}
};


/* Query plan of a single-table DELETE */
class Delete_plan : public Update_plan
{
  bool deleting_all_rows;
public:

  /* Construction functions */
  Delete_plan(MEM_ROOT *mem_root_arg) : 
    Update_plan(mem_root_arg), 
    deleting_all_rows(false)
  {}

  /* Set this query plan to be a plan to make a call to h->delete_all_rows() */
  void set_delete_all_rows(ha_rows rows_arg) 
  { 
    deleting_all_rows= true;
    scanned_rows= rows_arg;
  }
  void cancel_delete_all_rows()
  {
    deleting_all_rows= false;
  }

  Explain_delete* save_explain_delete_data(MEM_ROOT *mem_root, THD *thd);
};


class Query_arena_memroot;
/* The state of the lex parsing. This is saved in the THD struct */

struct LEX: public Query_tables_list
{
  SELECT_LEX_UNIT unit;                         /* most upper unit */
  SELECT_LEX select_lex;                        /* first SELECT_LEX */
  /* current SELECT_LEX in parsing */
  SELECT_LEX *current_select;
  /* list of all SELECT_LEX */
  SELECT_LEX *all_selects_list;
  
  /* Query Plan Footprint of a currently running select  */
  Explain_query *explain;

  // type information
  char *length,*dec;
  CHARSET_INFO *charset;

  LEX_STRING name;
  char *help_arg;
  char *backup_dir;				/* For RESTORE/BACKUP */
  char* to_log;                                 /* For PURGE MASTER LOGS TO */
  char* x509_subject,*x509_issuer,*ssl_cipher;
  String *wild; /* Wildcard in SHOW {something} LIKE 'wild'*/ 
  sql_exchange *exchange;
  select_result *result;
  LEX_STRING comment, ident;
  LEX_USER *grant_user;
  XID *xid;
  THD *thd;

  /* maintain a list of used plugins for this LEX */
  DYNAMIC_ARRAY plugins;
  plugin_ref plugins_static_buffer[INITIAL_LEX_PLUGIN_LIST_SIZE];

  bool text_string_is_7bit;

  /** SELECT of CREATE VIEW statement */
  LEX_STRING create_view_select;

  /** Start of 'ON table', in trigger statements.  */
  const char* raw_trg_on_table_name_begin;
  /** End of 'ON table', in trigger statements. */
  const char* raw_trg_on_table_name_end;

  /* Partition info structure filled in by PARTITION BY parse part */
  partition_info *part_info;

  /*
    The definer of the object being created (view, trigger, stored routine).
    I.e. the value of DEFINER clause.
  */
  LEX_USER *definer;

  List<Key_part_spec> ref_list;
  List<LEX_USER>      users_list;
  List<LEX_COLUMN>    columns;
  List<Item>	      *insert_list,field_list,value_list,update_list;
  List<List_item>     many_values;
  List<set_var_base>  var_list;
  List<set_var_base>  stmt_var_list; //SET_STATEMENT values
  List<set_var_base>  old_var_list; // SET STATEMENT old values
private:
  Query_arena_memroot *arena_for_set_stmt;
  MEM_ROOT *mem_root_for_set_stmt;
  void parse_error();
public:
  inline bool is_arena_for_set_stmt() {return arena_for_set_stmt != 0;}
  bool set_arena_for_set_stmt(Query_arena *backup);
  void reset_arena_for_set_stmt(Query_arena *backup);
  void free_arena_for_set_stmt();

  List<Item_func_set_user_var> set_var_list; // in-query assignment list
  List<Item_param>    param_list;
  List<LEX_STRING>    view_list; // view list (list of field names in view)
  List<LEX_STRING>   *column_list; // list of column names (in ANALYZE)
  List<LEX_STRING>   *index_list;  // list of index names (in ANALYZE)
  /*
    A stack of name resolution contexts for the query. This stack is used
    at parse time to set local name resolution contexts for various parts
    of a query. For example, in a JOIN ... ON (some_condition) clause the
    Items in 'some_condition' must be resolved only against the operands
    of the the join, and not against the whole clause. Similarly, Items in
    subqueries should be resolved against the subqueries (and outer queries).
    The stack is used in the following way: when the parser detects that
    all Items in some clause need a local context, it creates a new context
    and pushes it on the stack. All newly created Items always store the
    top-most context in the stack. Once the parser leaves the clause that
    required a local context, the parser pops the top-most context.
  */
  List<Name_resolution_context> context_stack;

  SQL_I_List<ORDER> proc_list;
  SQL_I_List<TABLE_LIST> auxiliary_table_list, save_list;
  Create_field	      *last_field;
  Item_sum *in_sum_func;
  udf_func udf;
  HA_CHECK_OPT   check_opt;			// check/repair options
  Table_specification_st create_info;
  Key *last_key;
  LEX_MASTER_INFO mi;				// used by CHANGE MASTER
  LEX_SERVER_OPTIONS server_options;
  LEX_STRING relay_log_connection_name;
  USER_RESOURCES mqh;
  LEX_RESET_SLAVE reset_slave_info;
  ulonglong type;
  ulong next_binlog_file_number;
  /* The following is used by KILL */
  killed_state kill_signal;
  killed_type  kill_type;
  /*
    This variable is used in post-parse stage to declare that sum-functions,
    or functions which have sense only if GROUP BY is present, are allowed.
    For example in a query
    SELECT ... FROM ...WHERE MIN(i) == 1 GROUP BY ... HAVING MIN(i) > 2
    MIN(i) in the WHERE clause is not allowed in the opposite to MIN(i)
    in the HAVING clause. Due to possible nesting of select construct
    the variable can contain 0 or 1 for each nest level.
  */
  nesting_map allow_sum_func;

  Sql_cmd *m_sql_cmd;

  /*
    Usually `expr` rule of yacc is quite reused but some commands better
    not support subqueries which comes standard with this rule, like
    KILL, HA_READ, CREATE/ALTER EVENT etc. Set this to `false` to get
    syntax error back.
  */
  bool expr_allows_subselect;
  /*
    A special command "PARSE_VCOL_EXPR" is defined for the parser 
    to translate a defining expression of a virtual column into an 
    Item object.
    The following flag is used to prevent other applications to use 
    this command.
  */
  bool parse_vcol_expr;

  enum SSL_type ssl_type;			/* defined in violite.h */
  enum enum_duplicates duplicates;
  enum enum_tx_isolation tx_isolation;
  enum enum_ha_read_modes ha_read_mode;
  union {
    enum ha_rkey_function ha_rkey_mode;
    enum xa_option_words xa_opt;
    bool with_admin_option;                     // GRANT role
    bool with_persistent_for_clause; // uses PERSISTENT FOR clause (in ANALYZE)
  };
  enum enum_var_type option_type;
  enum enum_view_create_mode create_view_mode;
  enum enum_drop_mode drop_mode;

  uint profile_query_id;
  uint profile_options;
  uint grant, grant_tot_col, which_columns;
  enum Foreign_key::fk_match_opt fk_match_option;
  enum Foreign_key::fk_option fk_update_opt;
  enum Foreign_key::fk_option fk_delete_opt;
  uint slave_thd_opt, start_transaction_opt;
  int nest_level;
  /*
    In LEX representing update which were transformed to multi-update
    stores total number of tables. For LEX representing multi-delete
    holds number of tables from which we will delete records.
  */
  uint table_count;
  uint8 describe;
  bool  analyze_stmt; /* TRUE<=> this is "ANALYZE $stmt" */
  bool  explain_json;
  /*
    A flag that indicates what kinds of derived tables are present in the
    query (0 if no derived tables, otherwise a combination of flags
    DERIVED_SUBQUERY and DERIVED_VIEW).
  */
  uint8 derived_tables;
  uint16 create_view_algorithm;
  uint8 create_view_check;
  uint8 context_analysis_only;
  bool local_file;
  bool check_exists;
  bool autocommit;
  bool verbose, no_write_to_binlog;

  enum enum_yes_no_unknown tx_chain, tx_release;
  bool safe_to_cache_query;
  bool subqueries, ignore;
  st_parsing_options parsing_options;
  Alter_info alter_info;
  /*
    For CREATE TABLE statement last element of table list which is not
    part of SELECT or LIKE part (i.e. either element for table we are
    creating or last of tables referenced by foreign keys).
  */
  TABLE_LIST *create_last_non_select_table;
  /* Prepared statements SQL syntax:*/
  LEX_STRING prepared_stmt_name; /* Statement name (in all queries) */
  /*
    Prepared statement query text or name of variable that holds the
    prepared statement (in PREPARE ... queries)
  */
  LEX_STRING prepared_stmt_code;
  /* If true, prepared_stmt_code is a name of variable that holds the query */
  bool prepared_stmt_code_is_varref;
  /* Names of user variables holding parameters (in EXECUTE) */
  List<LEX_STRING> prepared_stmt_params;
  sp_head *sphead;
  sp_name *spname;
  bool sp_lex_in_use;	/* Keep track on lex usage in SPs for error handling */
  bool all_privileges;
  bool proxy_priv;

  sp_pcontext *spcont;

  st_sp_chistics sp_chistics;

  Event_parse_data *event_parse_data;

  bool only_view;       /* used for SHOW CREATE TABLE/VIEW */
  /*
    field_list was created for view and should be removed before PS/SP
    rexecuton
  */
  bool empty_field_list_on_rset;
  /*
    view created to be run from definer (standard behaviour)
  */
  uint8 create_view_suid;
  /* Characterstics of trigger being created */
  st_trg_chistics trg_chistics;
  /*
    List of all items (Item_trigger_field objects) representing fields in
    old/new version of row in trigger. We use this list for checking whenever
    all such fields are valid at trigger creation time and for binding these
    fields to TABLE object at table open (altough for latter pointer to table
    being opened is probably enough).
  */
  SQL_I_List<Item_trigger_field> trg_table_fields;

  /*
    stmt_definition_begin is intended to point to the next word after
    DEFINER-clause in the following statements:
      - CREATE TRIGGER (points to "TRIGGER");
      - CREATE PROCEDURE (points to "PROCEDURE");
      - CREATE FUNCTION (points to "FUNCTION" or "AGGREGATE");
      - CREATE EVENT (points to "EVENT")

    This pointer is required to add possibly omitted DEFINER-clause to the
    DDL-statement before dumping it to the binlog.

    keyword_delayed_begin_offset is the offset to the beginning of the DELAYED
    keyword in INSERT DELAYED statement. keyword_delayed_end_offset is the
    offset to the character right after the DELAYED keyword.
  */
  union {
    const char *stmt_definition_begin;
    uint keyword_delayed_begin_offset;
  };

  union {
    const char *stmt_definition_end;
    uint keyword_delayed_end_offset;
  };

  /**
    Collects create options for KEY
  */
  engine_option_value *option_list;

  /**
    Helper pointer to the end of the list when parsing options for
      LEX::create_info.option_list (for table)
      LEX::last_field->option_list (for fields)
      LEX::option_list             (for indexes)
  */
  engine_option_value *option_list_last;

  /**
    During name resolution search only in the table list given by 
    Name_resolution_context::first_name_resolution_table and
    Name_resolution_context::last_name_resolution_table
    (see Item_field::fix_fields()). 
  */
  bool use_only_table_context;

  /*
    Reference to a struct that contains information in various commands
    to add/create/drop/change table spaces.
  */
  st_alter_tablespace *alter_tablespace_info;
  
  bool escape_used;
  bool is_lex_started; /* If lex_start() did run. For debugging. */

  /*
    The set of those tables whose fields are referenced in all subqueries
    of the query.
    TODO: possibly this it is incorrect to have used tables in LEX because
    with subquery, it is not clear what does the field mean. To fix this
    we should aggregate used tables information for selected expressions
    into the select_lex.
  */
  table_map  used_tables;
  /**
    Maximum number of rows and/or keys examined by the query, both read,
    changed or written. This is the argument of LIMIT ROWS EXAMINED.
    The limit is represented by two variables - the Item is needed because
    in case of parameters we have to delay its evaluation until execution.
    Once evaluated, its value is stored in examined_rows_limit_cnt.
  */
  Item *limit_rows_examined;
  ulonglong limit_rows_examined_cnt;
  inline void set_limit_rows_examined()
  {
    if (limit_rows_examined)
      limit_rows_examined_cnt= limit_rows_examined->val_uint();
    else
      limit_rows_examined_cnt= ULONGLONG_MAX;
  }


  inline void free_set_stmt_mem_root()
  {
    DBUG_ASSERT(!is_arena_for_set_stmt());
    if (mem_root_for_set_stmt)
    {
      free_root(mem_root_for_set_stmt, MYF(0));
      delete mem_root_for_set_stmt;
      mem_root_for_set_stmt= 0;
    }
  }

  LEX();

  virtual ~LEX()
  {
    free_set_stmt_mem_root();
    destroy_query_tables_list();
    plugin_unlock_list(NULL, (plugin_ref *)plugins.buffer, plugins.elements);
    delete_dynamic(&plugins);
  }

  inline bool is_ps_or_view_context_analysis()
  {
    return (context_analysis_only &
            (CONTEXT_ANALYSIS_ONLY_PREPARE |
             CONTEXT_ANALYSIS_ONLY_VCOL_EXPR |
             CONTEXT_ANALYSIS_ONLY_VIEW));
  }

  inline bool is_view_context_analysis()
  {
    return (context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW);
  }

  inline void uncacheable(uint8 cause)
  {
    safe_to_cache_query= 0;

    /*
      There are no sense to mark select_lex and union fields of LEX,
      but we should merk all subselects as uncacheable from current till
      most upper
    */
    SELECT_LEX *sl;
    SELECT_LEX_UNIT *un;
    for (sl= current_select, un= sl->master_unit();
	 un != &unit;
	 sl= sl->outer_select(), un= sl->master_unit())
    {
      sl->uncacheable|= cause;
      un->uncacheable|= cause;
    }
    select_lex.uncacheable|= cause;
  }
  void set_trg_event_type_for_tables();

  TABLE_LIST *unlink_first_table(bool *link_to_local);
  void link_first_table_back(TABLE_LIST *first, bool link_to_local);
  void first_lists_tables_same();

  bool can_be_merged();
  bool can_use_merged();
  bool can_not_use_merged();
  bool only_view_structure();
  bool need_correct_ident();
  uint8 get_effective_with_check(TABLE_LIST *view);
  /*
    Is this update command where 'WHITH CHECK OPTION' clause is important

    SYNOPSIS
      LEX::which_check_option_applicable()

    RETURN
      TRUE   have to take 'WHITH CHECK OPTION' clause into account
      FALSE  'WHITH CHECK OPTION' clause do not need
  */
  inline bool which_check_option_applicable()
  {
    switch (sql_command) {
    case SQLCOM_UPDATE:
    case SQLCOM_UPDATE_MULTI:
    case SQLCOM_DELETE:
    case SQLCOM_DELETE_MULTI:
    case SQLCOM_INSERT:
    case SQLCOM_INSERT_SELECT:
    case SQLCOM_REPLACE:
    case SQLCOM_REPLACE_SELECT:
    case SQLCOM_LOAD:
      return TRUE;
    default:
      return FALSE;
    }
  }

  void cleanup_after_one_table_open();

  bool push_context(Name_resolution_context *context, MEM_ROOT *mem_root)
  {
    return context_stack.push_front(context, mem_root);
  }

  void pop_context()
  {
    context_stack.pop();
  }

  bool copy_db_to(char **p_db, size_t *p_db_length) const;

  Name_resolution_context *current_context()
  {
    return context_stack.head();
  }
  /*
    Restore the LEX and THD in case of a parse error.
  */
  static void cleanup_lex_after_parse_error(THD *thd);

  void reset_n_backup_query_tables_list(Query_tables_list *backup);
  void restore_backup_query_tables_list(Query_tables_list *backup);

  bool table_or_sp_used();
  bool is_partition_management() const;

  /**
    @brief check if the statement is a single-level join
    @return result of the check
      @retval TRUE  The statement doesn't contain subqueries, unions and 
                    stored procedure calls.
      @retval FALSE There are subqueries, UNIONs or stored procedure calls.
  */
  bool is_single_level_stmt() 
  { 
    /* 
      This check exploits the fact that the last added to all_select_list is
      on its top. So select_lex (as the first added) will be at the tail 
      of the list.
    */ 
    if (&select_lex == all_selects_list && !sroutines.records)
    {
      DBUG_ASSERT(!all_selects_list->next_select_in_list());
      return TRUE;
    }
    return FALSE;
  }

  bool save_prep_leaf_tables();

  int print_explain(select_result_sink *output, uint8 explain_flags,
                    bool is_analyze, bool *printed_anything);
  void restore_set_statement_var();

  void init_last_field(Create_field *field, const char *name, CHARSET_INFO *cs);
  void set_last_field_type(enum enum_field_types type);
  bool set_bincmp(CHARSET_INFO *cs, bool bin);
  // Check if "KEY IF NOT EXISTS name" used outside of ALTER context
  bool check_add_key(DDL_options_st ddl)
  {
    if (ddl.if_not_exists() && sql_command != SQLCOM_ALTER_TABLE)
    {
      parse_error();
      return true;
    }
    return false;
  }
  // Add a key as a part of CREATE TABLE or ALTER TABLE
  bool add_key(Key::Keytype key_type, const LEX_STRING &key_name,
               ha_key_alg algorithm, DDL_options_st ddl)
  {
    if (check_add_key(ddl) ||
        !(last_key= new Key(key_type, key_name, algorithm, false, ddl)))
      return true;
    alter_info.key_list.push_back(last_key);
    return false;
  }
  // Add a key for a CREATE INDEX statement
  bool add_create_index(Key::Keytype key_type, const LEX_STRING &key_name,
                        ha_key_alg algorithm, DDL_options_st ddl)
  {
    if (check_create_options(ddl) ||
       !(last_key= new Key(key_type, key_name, algorithm, false, ddl)))
      return true;
    alter_info.key_list.push_back(last_key);
    return false;
  }
  void set_command(enum_sql_command command,
                   DDL_options_st options)
  {
    sql_command= command;
    create_info.set(options);
  }
  void set_command(enum_sql_command command,
                   uint scope,
                   DDL_options_st options)
  {
    set_command(command, options);
    create_info.options|= scope; // HA_LEX_CREATE_TMP_TABLE or 0
  }
  bool check_create_options(DDL_options_st options)
  {
    if (options.or_replace() && options.if_not_exists())
    {
      my_error(ER_WRONG_USAGE, MYF(0), "OR REPLACE", "IF NOT EXISTS");
      return true;
    }
    return false;
  }
  bool add_create_options_with_check(DDL_options_st options)
  {
    create_info.add(options);
    return check_create_options(create_info);
  }
  bool set_command_with_check(enum_sql_command command,
                              uint scope,
                              DDL_options_st options)
  {
    set_command(command, scope, options);
    return check_create_options(options);
  }
  bool set_command_with_check(enum_sql_command command, DDL_options_st options)
  {
    set_command(command, options);
    return check_create_options(options);
  }
  /*
    DROP shares lex->create_info to store TEMPORARY and IF EXISTS options
    to save on extra initialization in lex_start().
    Add some wrappers, to avoid direct use of lex->create_info in the
    caller code processing DROP statements (which might look confusing).
  */
  bool tmp_table() const { return create_info.tmp_table(); }
  bool if_exists() const { return create_info.if_exists(); }
};


/**
  Set_signal_information is a container used in the parsed tree to represent
  the collection of assignments to condition items in the SIGNAL and RESIGNAL
  statements.
*/
class Set_signal_information
{
public:
  /** Empty default constructor, use clear() */
 Set_signal_information() {} 

  /** Copy constructor. */
  Set_signal_information(const Set_signal_information& set);

  /** Destructor. */
  ~Set_signal_information()
  {}

  /** Clear all items. */
  void clear();

  /**
    For each condition item assignment, m_item[] contains the parsed tree
    that represents the expression assigned, if any.
    m_item[] is an array indexed by Diag_condition_item_name.
  */
  Item *m_item[LAST_DIAG_SET_PROPERTY+1];
};


/**
  The internal state of the syntax parser.
  This object is only available during parsing,
  and is private to the syntax parser implementation (sql_yacc.yy).
*/
class Yacc_state
{
public:
  Yacc_state()
  {
    reset();
  }

  void reset()
  {
    yacc_yyss= NULL;
    yacc_yyvs= NULL;
    m_set_signal_info.clear();
    m_lock_type= TL_READ_DEFAULT;
    m_mdl_type= MDL_SHARED_READ;
  }

  ~Yacc_state();

  /**
    Reset part of the state which needs resetting before parsing
    substatement.
  */
  void reset_before_substatement()
  {
    m_lock_type= TL_READ_DEFAULT;
    m_mdl_type= MDL_SHARED_READ;
  }

  /**
    Bison internal state stack, yyss, when dynamically allocated using
    my_yyoverflow().
  */
  uchar *yacc_yyss;

  /**
    Bison internal semantic value stack, yyvs, when dynamically allocated using
    my_yyoverflow().
  */
  uchar *yacc_yyvs;

  /**
    Fragments of parsed tree,
    used during the parsing of SIGNAL and RESIGNAL.
  */
  Set_signal_information m_set_signal_info;

  /**
    Type of lock to be used for tables being added to the statement's
    table list in table_factor, table_alias_ref, single_multi and
    table_wild_one rules.
    Statements which use these rules but require lock type different
    from one specified by this member have to override it by using
    st_select_lex::set_lock_for_tables() method.

    The default value of this member is TL_READ_DEFAULT. The only two
    cases in which we change it are:
    - When parsing SELECT HIGH_PRIORITY.
    - Rule for DELETE. In which we use this member to pass information
      about type of lock from delete to single_multi part of rule.

    We should try to avoid introducing new use cases as we would like
    to get rid of this member eventually.
  */
  thr_lock_type m_lock_type;

  /**
    The type of requested metadata lock for tables added to
    the statement table list.
  */
  enum_mdl_type m_mdl_type;

  /*
    TODO: move more attributes from the LEX structure here.
  */
};

/**
  Input parameters to the parser.
*/
struct Parser_input
{
  bool m_compute_digest;

  Parser_input()
    : m_compute_digest(false)
  {}
};

/**
  Internal state of the parser.
  The complete state consist of:
  - state data used during lexical parsing,
  - state data used during syntactic parsing.
*/
class Parser_state
{
public:
  Parser_state()
    : m_yacc()
  {}

  /**
     Object initializer. Must be called before usage.

     @retval FALSE OK
     @retval TRUE  Error
  */
  bool init(THD *thd, char *buff, unsigned int length)
  {
    return m_lip.init(thd, buff, length);
  }

  ~Parser_state()
  {}

  Parser_input m_input;
  Lex_input_stream m_lip;
  Yacc_state m_yacc;

  /**
    Current performance digest instrumentation. 
  */
  PSI_digest_locker* m_digest_psi;

  void reset(char *found_semicolon, unsigned int length)
  {
    m_lip.reset(found_semicolon, length);
    m_yacc.reset();
  }
};

extern sql_digest_state *
digest_add_token(sql_digest_state *state, uint token, LEX_YYSTYPE yylval);

extern sql_digest_state *
digest_reduce_token(sql_digest_state *state, uint token_left, uint token_right);

struct st_lex_local: public LEX, public Sql_alloc
{
};

extern void lex_init(void);
extern void lex_free(void);
extern void lex_start(THD *thd);
extern void lex_end(LEX *lex);
void end_lex_with_single_table(THD *thd, TABLE *table, LEX *old_lex);
int init_lex_with_single_table(THD *thd, TABLE *table, LEX *lex);
extern int MYSQLlex(union YYSTYPE *yylval, THD *thd);

extern void trim_whitespace(CHARSET_INFO *cs, LEX_STRING *str);

extern bool is_lex_native_function(const LEX_STRING *name);

/**
  @} (End of group Semantic_Analysis)
*/

void my_missing_function_error(const LEX_STRING &token, const char *name);
bool is_keyword(const char *name, uint len);

#endif /* MYSQL_SERVER */
#endif /* SQL_LEX_INCLUDED */