Added more tests for new UPDATE ... ORDER BY ... LIMIT optimization

heap/_check.c:
  Change arguments to ha_key_cmp
heap/hp_create.c:
  Change arguments to ha_key_cmp
include/my_base.h:
  Remove SEARCH_RETURN_B_POS and instead always send an array to ha_key_cmp() as last argument
myisam/mi_check.c:
  Change arguments to ha_key_cmp
myisam/mi_rnext_same.c:
  Change arguments to ha_key_cmp
myisam/mi_search.c:
  Change arguments to ha_key_cmp
myisam/mi_write.c:
  Change arguments to ha_key_cmp
myisammrg/myrg_queue.c:
  Change arguments to ha_key_cmp
mysys/my_handler.c:
  Remove SEARCH_RETURN_B_POS and instead always send an array to ha_key_cmp() as last argument
  (This removes an if in a loop at the expensive of an int on the stack)
sql/records.cc:
  Simplify new rr_index() code
  Create common error handling function for rr_() functions.
  Remove loop from rr_index() as handler::index_next() can never return HA_ERR_RECORD_DELETED
sql/sql_load.cc:
  Simplify
sql/sql_update.cc:
  Simplify code
  Fixed bug when one is updating an index column that could be used with ORDER BY
sql/structs.h:
  Removed not needed structure element

4 files changed, 96 insertions, 118 deletions

diff --git a/sql/records.cc b/sql/records.cc
index 9150024d4b8..7e4a808f0c3 100644
--- a/sql/records.cc
+++ b/sql/records.cc
@@ -28,11 +28,10 @@ static int rr_from_pointers(READ_RECORD *info);
 static int rr_from_cache(READ_RECORD *info);
 static int init_rr_cache(READ_RECORD *info);
 static int rr_cmp(uchar *a,uchar *b);
-
+static int rr_index_first(READ_RECORD *info);
 static int rr_index(READ_RECORD *info);
 
 
-
 /*
   Initialize READ_RECORD structure to perform full index scan
 
@@ -58,26 +57,19 @@ void init_read_record_idx(READ_RECORD *info, THD *thd, TABLE *table,
                           bool print_error, uint idx)
 {
   bzero((char*) info,sizeof(*info));
-  info->thd=thd;
-  info->table=table;
-  info->file= table->file;
-  info->forms= &info->table;		/* Only one table */
-    
+  info->table= table;
+  info->file=  table->file;
   info->record= table->record[0];
-  info->ref_length= table->file->ref_length;
+  info->print_error= print_error;
 
-  info->select=NULL;
-  info->print_error=print_error;
-  info->ignore_not_found_rows= 0;
   table->status=0;			/* And it's always found */
-
   if (!table->file->inited)
   {
     table->file->ha_index_init(idx);
     table->file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY);
   }
-  info->read_record= rr_index;
-  info->first= TRUE;
+  /* read_record will be changed to rr_index in rr_index_first */
+  info->read_record= rr_index_first;
 }
 
 
@@ -204,6 +196,21 @@ void end_read_record(READ_RECORD *info)
   }
 }
 
+static int rr_handle_error(READ_RECORD *info, int error)
+{
+  if (error == HA_ERR_END_OF_FILE)
+    error= -1;
+  else
+  {
+    if (info->print_error)
+      info->table->file->print_error(error, MYF(0));
+    if (error < 0)                            // Fix negative BDB errno
+      error= 1;
+  }
+  return error;
+}
+
+
 	/* Read a record from head-database */
 
 static int rr_quick(READ_RECORD *info)
@@ -218,15 +225,7 @@ static int rr_quick(READ_RECORD *info)
     }
     if (tmp != HA_ERR_RECORD_DELETED)
     {
-      if (tmp == HA_ERR_END_OF_FILE)
-        tmp= -1;
-      else
-      {
-        if (info->print_error)
-          info->file->print_error(tmp,MYF(0));
-        if (tmp < 0)				// Fix negative BDB errno
-          tmp=1;
-      }
+      tmp= rr_handle_error(info, tmp);
       break;
     }
   }
@@ -235,7 +234,31 @@ static int rr_quick(READ_RECORD *info)
 
 
 /*
-  A READ_RECORD::read_record implementation that reads index sequentially
+  Reads first row in an index scan
+
+  SYNOPSIS
+    rr_index_first()
+    info  	Scan info
+  
+  RETURN
+    0   Ok
+    -1  End of records 
+    1   Error   
+*/
+
+
+static int rr_index_first(READ_RECORD *info)
+{
+  int tmp= info->file->index_first(info->record);
+  info->read_record= rr_index;
+  if (tmp)
+    tmp= rr_handle_error(info, tmp);
+  return tmp;
+}
+
+
+/*
+  Reads index sequentially after first row
 
   SYNOPSIS
     rr_index()
@@ -251,43 +274,16 @@ static int rr_quick(READ_RECORD *info)
     1   Error   
 */
 
+
 static int rr_index(READ_RECORD *info)
 {
-  int tmp;
-  while (1)
-  {
-    if (info->first)
-    {
-      info->first= FALSE;
-      tmp= info->file->index_first(info->record);
-    }
-    else
-      tmp= info->file->index_next(info->record);
-    
-    if (!tmp)
-      break;
-    if (info->thd->killed)
-    {
-      my_error(ER_SERVER_SHUTDOWN,MYF(0));
-      return 1;
-    }
-    if (tmp != HA_ERR_RECORD_DELETED)
-    {
-      if (tmp == HA_ERR_END_OF_FILE)
-        tmp= -1;
-      else
-      {
-        if (info->print_error)
-          info->table->file->print_error(tmp,MYF(0));
-        if (tmp < 0)                            // Fix negative BDB errno
-          tmp=1;
-      }
-      break;
-    }
-  }
+  int tmp= info->file->index_next(info->record);
+  if (tmp)
+    tmp= rr_handle_error(info, tmp);
   return tmp;
 }
 
+
 static int rr_sequential(READ_RECORD *info)
 {
   int tmp;
@@ -298,17 +294,13 @@ static int rr_sequential(READ_RECORD *info)
       my_error(ER_SERVER_SHUTDOWN,MYF(0));
       return 1;
     }
+    /*
+      rnd_next can return RECORD_DELETED for MyISAM when one thread is
+      reading and another deleting without locks.
+    */
     if (tmp != HA_ERR_RECORD_DELETED)
     {
-      if (tmp == HA_ERR_END_OF_FILE)
-	tmp= -1;
-      else
-      {
-	if (info->print_error)
-	  info->table->file->print_error(tmp,MYF(0));
-	if (tmp < 0)				// Fix negative BDB errno
-	  tmp=1;
-      }
+      tmp= rr_handle_error(info, tmp);
       break;
     }
   }
@@ -319,23 +311,18 @@ static int rr_sequential(READ_RECORD *info)
 static int rr_from_tempfile(READ_RECORD *info)
 {
   int tmp;
-tryNext:
-  if (my_b_read(info->io_cache,info->ref_pos,info->ref_length))
-    return -1;					/* End of file */
-  if ((tmp=info->file->rnd_pos(info->record,info->ref_pos)))
+  for (;;)
   {
-    if (tmp == HA_ERR_END_OF_FILE)
-      tmp= -1;
-    else if (tmp == HA_ERR_RECORD_DELETED ||
-	     (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
-      goto tryNext;
-    else
-    {
-      if (info->print_error)
-	info->file->print_error(tmp,MYF(0));
-      if (tmp < 0)				// Fix negative BDB errno
-	tmp=1;
-    }
+    if (my_b_read(info->io_cache,info->ref_pos,info->ref_length))
+      return -1;					/* End of file */
+    if (!(tmp=info->file->rnd_pos(info->record,info->ref_pos)))
+      break;
+    /* The following is extremely unlikely to happen */
+    if (tmp == HA_ERR_RECORD_DELETED ||
+        (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
+      continue;
+    tmp= rr_handle_error(info, tmp);
+    break;
   }
   return tmp;
 } /* rr_from_tempfile */
@@ -373,26 +360,23 @@ static int rr_from_pointers(READ_RECORD *info)
 {
   int tmp;
   byte *cache_pos;
-tryNext:
-  if (info->cache_pos == info->cache_end)
-    return -1;					/* End of file */
-  cache_pos=info->cache_pos;
-  info->cache_pos+=info->ref_length;
 
-  if ((tmp=info->file->rnd_pos(info->record,cache_pos)))
+  for (;;)
   {
-    if (tmp == HA_ERR_END_OF_FILE)
-      tmp= -1;
-    else if (tmp == HA_ERR_RECORD_DELETED ||
-	     (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
-      goto tryNext;
-    else
-    {
-      if (info->print_error)
-	info->file->print_error(tmp,MYF(0));
-      if (tmp < 0)				// Fix negative BDB errno
-	tmp=1;
-    }
+    if (info->cache_pos == info->cache_end)
+      return -1;					/* End of file */
+    cache_pos= info->cache_pos;
+    info->cache_pos+= info->ref_length;
+
+    if (!(tmp=info->file->rnd_pos(info->record,cache_pos)))
+      break;
+
+    /* The following is extremely unlikely to happen */
+    if (tmp == HA_ERR_RECORD_DELETED ||
+        (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
+      continue;
+    tmp= rr_handle_error(info, tmp);
+    break;
   }
   return tmp;
 }
diff --git a/sql/sql_load.cc b/sql/sql_load.cc
index 3b7c6608aef..aa4ea3e6c8c 100644
--- a/sql/sql_load.cc
+++ b/sql/sql_load.cc
@@ -818,11 +818,8 @@ int READ_INFO::read_field()
           *to++ = (byte) unescape((char) chr);
           continue;
         }
-        else
-        {
-          PUSH(chr);
-          chr= escape_char;
-        }
+        PUSH(chr);
+        chr= escape_char;
       }
 #ifdef ALLOW_LINESEPARATOR_IN_STRINGS
       if (chr == line_term_char)
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index c30749677d6..b6bce800b0e 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -148,7 +148,7 @@ int mysql_update(THD *thd,
   }
   if (!select && limit != HA_POS_ERROR)
   {
-    if (MAX_KEY != (used_index= get_index_for_order(table, order, limit)))
+    if ((used_index= get_index_for_order(table, order, limit)) != MAX_KEY)
       need_sort= FALSE;
   }
   /* If running in safe sql mode, don't allow updates without keys */
@@ -171,14 +171,14 @@ int mysql_update(THD *thd,
     used_key_is_modified= (!select->quick->unique_key_range() &&
 			   check_if_key_used(table, used_index, fields));
   }
-  else if (used_index != MAX_KEY)
+  else
   {
-    used_key_is_modified= check_if_key_used(table, used_index, fields);
+    used_key_is_modified= 0;
+    if (used_index == MAX_KEY)                  // no index for sort order
+      used_index= table->file->key_used_on_scan;
+    if (used_index != MAX_KEY)
+      used_key_is_modified= check_if_key_used(table, used_index, fields);
   }
-  else if ((used_index=table->file->key_used_on_scan) < MAX_KEY)
-    used_key_is_modified=check_if_key_used(table, used_index, fields);
-  else
-    used_key_is_modified=0;
 
   if (used_key_is_modified || order)
   {
@@ -190,11 +190,11 @@ int mysql_update(THD *thd,
     if (used_index < MAX_KEY && old_used_keys.is_set(used_index))
     {
       table->key_read=1;
-      table->file->extra(HA_EXTRA_KEYREAD); //todo: psergey: check
+      table->file->extra(HA_EXTRA_KEYREAD);
     }
 
     /* note: can actually avoid sorting below.. */
-    if (order && need_sort)
+    if (order && (need_sort || used_key_is_modified))
     {
       /*
 	Doing an ORDER BY;  Let filesort find and sort the rows we are going
@@ -204,6 +204,7 @@ int mysql_update(THD *thd,
       SORT_FIELD  *sortorder;
       ha_rows examined_rows;
 
+      used_index= MAX_KEY;                   // For call to init_read_record()
       table->sort.io_cache = (IO_CACHE *) my_malloc(sizeof(IO_CACHE),
 						    MYF(MY_FAE | MY_ZEROFILL));
       if (!(sortorder=make_unireg_sortorder(order, &length)) ||
@@ -265,10 +266,7 @@ int mysql_update(THD *thd,
 	error= 1;				// Aborted
       limit= tmp_limit;
       end_read_record(&info);
-
-      /* if we got here we must not use index in the main update loop below */
-      used_index= MAX_KEY;
-      
+     
       /* Change select to use tempfile */
       if (select)
       {
diff --git a/sql/structs.h b/sql/structs.h
index 4a88a17cdd0..081ada88bf7 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -132,7 +132,6 @@ typedef struct st_read_record {			/* Parameter to read_record */
   byte	*cache,*cache_pos,*cache_end,*read_positions;
   IO_CACHE *io_cache;
   bool print_error, ignore_not_found_rows;
-  bool first; /* used only with rr_index_read */
 } READ_RECORD;