sql_update.cc

/* Copyright (C) 2000-2006 MySQL AB

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/*
  Single table and multi table updates of tables.
  Multi-table updates were introduced by Sinisa & Monty
*/

#include "mysql_priv.h"
#include "sql_select.h"
#include "sp_head.h"
#include "sql_trigger.h"

/* Return 0 if row hasn't changed */

bool compare_record(TABLE *table)
{
  if (table->s->blob_fields + table->s->varchar_fields == 0)
    return cmp_record(table,record[1]);
  /* Compare null bits */
  if (memcmp(table->null_flags,
	     table->null_flags+table->s->rec_buff_length,
	     table->s->null_bytes))
    return TRUE;				// Diff in NULL value
  /* Compare updated fields */
  for (Field **ptr= table->field ; *ptr ; ptr++)
  {
    if (bitmap_is_set(table->write_set, (*ptr)->field_index) &&
	(*ptr)->cmp_binary_offset(table->s->rec_buff_length))
      return TRUE;
  }
  return FALSE;
}


/*
  check that all fields are real fields

  SYNOPSIS
    check_fields()
    thd             thread handler
    items           Items for check

  RETURN
    TRUE  Items can't be used in UPDATE
    FALSE Items are OK
*/

static bool check_fields(THD *thd, List<Item> &items)
{
  List_iterator<Item> it(items);
  Item *item;
  Item_field *field;

  while ((item= it++))
  {
    if (!(field= item->filed_for_view_update()))
    {
      /* item has name, because it comes from VIEW SELECT list */
      my_error(ER_NONUPDATEABLE_COLUMN, MYF(0), item->name);
      return TRUE;
    }
    /*
      we make temporary copy of Item_field, to avoid influence of changing
      result_field on Item_ref which refer on this field
    */
    thd->change_item_tree(it.ref(), new Item_field(thd, field));
  }
  return FALSE;
}


/*
  Process usual UPDATE

  SYNOPSIS
    mysql_update()
    thd			thread handler
    fields		fields for update
    values		values of fields for update
    conds		WHERE clause expression
    order_num		number of elemen in ORDER BY clause
    order		ORDER BY clause list
    limit		limit clause
    handle_duplicates	how to handle duplicates

  RETURN
    0  - OK
    2  - privilege check and openning table passed, but we need to convert to
         multi-update because of view substitution
    1  - error
*/

int mysql_update(THD *thd,
                 TABLE_LIST *table_list,
                 List<Item> &fields,
		 List<Item> &values,
                 COND *conds,
                 uint order_num, ORDER *order,
		 ha_rows limit,
		 enum enum_duplicates handle_duplicates, bool ignore)
{
  bool		using_limit= limit != HA_POS_ERROR;
  bool		safe_update= test(thd->options & OPTION_SAFE_UPDATES);
  bool		used_key_is_modified, transactional_table, will_batch;
  bool		can_compare_record;
  int           res;
  int		error, loc_error;
  uint		used_index= MAX_KEY, dup_key_found;
  bool          need_sort= TRUE;
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  uint		want_privilege;
#endif
  uint          table_count= 0;
  ha_rows	updated, found;
  key_map	old_covering_keys;
  TABLE		*table;
  SQL_SELECT	*select;
  READ_RECORD	info;
  SELECT_LEX    *select_lex= &thd->lex->select_lex;
  bool          need_reopen;
  ulonglong     id;
  List<Item> all_fields;
  DBUG_ENTER("mysql_update");

  for ( ; ; )
  {
    if (open_tables(thd, &table_list, &table_count, 0))
      DBUG_RETURN(1);

    if (table_list->multitable_view)
    {
      DBUG_ASSERT(table_list->view != 0);
      DBUG_PRINT("info", ("Switch to multi-update"));
      /* pass counter value */
      thd->lex->table_count= table_count;
      /* convert to multiupdate */
      DBUG_RETURN(2);
    }
    if (!lock_tables(thd, table_list, table_count, &need_reopen))
      break;
    if (!need_reopen)
      DBUG_RETURN(1);
    close_tables_for_reopen(thd, &table_list);
  }

  if (mysql_handle_derived(thd->lex, &mysql_derived_prepare) ||
      (thd->fill_derived_tables() &&
       mysql_handle_derived(thd->lex, &mysql_derived_filling)))
    DBUG_RETURN(1);

  thd->proc_info="init";
  table= table_list->table;

  /* Calculate "table->covering_keys" based on the WHERE */
  table->covering_keys= table->s->keys_in_use;
  table->quick_keys.clear_all();

#ifndef NO_EMBEDDED_ACCESS_CHECKS
  /* Force privilege re-checking for views after they have been opened. */
  want_privilege= (table_list->view ? UPDATE_ACL :
                   table_list->grant.want_privilege);
#endif
  if (mysql_prepare_update(thd, table_list, &conds, order_num, order))
    DBUG_RETURN(1);

  old_covering_keys= table->covering_keys;		// Keys used in WHERE
  /* Check the fields we are going to modify */
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  table_list->grant.want_privilege= table->grant.want_privilege= want_privilege;
  table_list->register_want_access(want_privilege);
#endif
  if (setup_fields_with_no_wrap(thd, 0, fields, MARK_COLUMNS_WRITE, 0, 0))
    DBUG_RETURN(1);                     /* purecov: inspected */
  if (table_list->view && check_fields(thd, fields))
  {
    DBUG_RETURN(1);
  }
  if (!table_list->updatable || check_key_in_view(thd, table_list))
  {
    my_error(ER_NON_UPDATABLE_TABLE, MYF(0), table_list->alias, "UPDATE");
    DBUG_RETURN(1);
  }
  if (table->timestamp_field)
  {
    // Don't set timestamp column if this is modified
    if (bitmap_is_set(table->write_set,
                      table->timestamp_field->field_index))
      table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;
    else
    {
      if (table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_UPDATE ||
          table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_BOTH)
        bitmap_set_bit(table->write_set,
                       table->timestamp_field->field_index);
    }
  }

#ifndef NO_EMBEDDED_ACCESS_CHECKS
  /* Check values */
  table_list->grant.want_privilege= table->grant.want_privilege=
    (SELECT_ACL & ~table->grant.privilege);
#endif
  if (setup_fields(thd, 0, values, MARK_COLUMNS_READ, 0, 0))
  {
    free_underlaid_joins(thd, select_lex);
    DBUG_RETURN(1);				/* purecov: inspected */
  }

  if (select_lex->inner_refs_list.elements &&
    fix_inner_refs(thd, all_fields, select_lex, select_lex->ref_pointer_array))
    DBUG_RETURN(-1);

  if (conds)
  {
    Item::cond_result cond_value;
    conds= remove_eq_conds(thd, conds, &cond_value);
    if (cond_value == Item::COND_FALSE)
      limit= 0;                                   // Impossible WHERE
  }
  // Don't count on usage of 'only index' when calculating which key to use
  table->covering_keys.clear_all();

#ifdef WITH_PARTITION_STORAGE_ENGINE
  if (prune_partitions(thd, table, conds))
  {
    free_underlaid_joins(thd, select_lex);
    send_ok(thd);				// No matching records
    DBUG_RETURN(0);
  }
#endif
  /* Update the table->file->stats.records number */
  table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

  select= make_select(table, 0, 0, conds, 0, &error);
  if (error || !limit ||
      (select && select->check_quick(thd, safe_update, limit)))
  {
    delete select;
    free_underlaid_joins(thd, select_lex);
    if (error)
    {
      DBUG_RETURN(1);				// Error in where
    }
    send_ok(thd);				// No matching records
    DBUG_RETURN(0);
  }
  if (!select && limit != HA_POS_ERROR)
  {
    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 */
  if (table->quick_keys.is_clear_all())
  {
    thd->server_status|=SERVER_QUERY_NO_INDEX_USED;
    if (safe_update && !using_limit)
    {
      my_message(ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE,
		 ER(ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE), MYF(0));
      goto err;
    }
  }
  init_ftfuncs(thd, select_lex, 1);

  table->mark_columns_needed_for_update();

  /* Check if we are modifying a key that we are used to search with */
  
  if (select && select->quick)
  {
    used_index= select->quick->index;
    used_key_is_modified= (!select->quick->unique_key_range() &&
                          select->quick->is_keys_used(table->write_set));
  }
  else
  {
    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= is_key_used(table, used_index, table->write_set);
  }


#ifdef WITH_PARTITION_STORAGE_ENGINE
  if (used_key_is_modified || order ||
      partition_key_modified(table, table->write_set))
#else
  if (used_key_is_modified || order)
#endif
  {
    /*
      We can't update table directly;  We must first search after all
      matching rows before updating the table!
    */
    if (used_index < MAX_KEY && old_covering_keys.is_set(used_index))
    {
      table->key_read=1;
      table->mark_columns_used_by_index(used_index);
    }
    else
    {
      table->use_all_columns();
    }

    /* note: We avoid sorting avoid if we sort on the used index */
    if (order && (need_sort || used_key_is_modified))
    {
      /*
	Doing an ORDER BY;  Let filesort find and sort the rows we are going
	to update
        NOTE: filesort will call table->prepare_for_position()
      */
      uint         length= 0;
      SORT_FIELD  *sortorder;
      ha_rows examined_rows;

      table->sort.io_cache = (IO_CACHE *) my_malloc(sizeof(IO_CACHE),
						    MYF(MY_FAE | MY_ZEROFILL));
      if (!(sortorder=make_unireg_sortorder(order, &length, NULL)) ||
          (table->sort.found_records= filesort(thd, table, sortorder, length,
                                               select, limit, 1,
                                               &examined_rows))
          == HA_POS_ERROR)
      {
	goto err;
      }
      /*
	Filesort has already found and selected the rows we want to update,
	so we don't need the where clause
      */
      delete select;
      select= 0;
    }
    else
    {
      /*
	We are doing a search on a key that is updated. In this case
	we go trough the matching rows, save a pointer to them and
	update these in a separate loop based on the pointer.
      */

      IO_CACHE tempfile;
      if (open_cached_file(&tempfile, mysql_tmpdir,TEMP_PREFIX,
			   DISK_BUFFER_SIZE, MYF(MY_WME)))
	goto err;

      /* If quick select is used, initialize it before retrieving rows. */
      if (select && select->quick && select->quick->reset())
        goto err;
      table->file->try_semi_consistent_read(1);

      /*
        When we get here, we have one of the following options:
        A. used_index == MAX_KEY
           This means we should use full table scan, and start it with
           init_read_record call
        B. used_index != MAX_KEY
           B.1 quick select is used, start the scan with init_read_record
           B.2 quick select is not used, this is full index scan (with LIMIT)
               Full index scan must be started with init_read_record_idx
      */

      if (used_index == MAX_KEY || (select && select->quick))
        init_read_record(&info,thd,table,select,0,1);
      else
        init_read_record_idx(&info, thd, table, 1, used_index);

      thd->proc_info="Searching rows for update";
      uint tmp_limit= limit;

      while (!(error=info.read_record(&info)) && !thd->killed)
      {
	if (!(select && select->skip_record()))
	{
          if (table->file->was_semi_consistent_read())
	    continue;  /* repeat the read of the same row if it still exists */

	  table->file->position(table->record[0]);
	  if (my_b_write(&tempfile,table->file->ref,
			 table->file->ref_length))
	  {
	    error=1; /* purecov: inspected */
	    break; /* purecov: inspected */
	  }
	  if (!--limit && using_limit)
	  {
	    error= -1;
	    break;
	  }
	}
	else
	  table->file->unlock_row();
      }
      if (thd->killed && !error)
	error= 1;				// Aborted
      limit= tmp_limit;
      table->file->try_semi_consistent_read(0);
      end_read_record(&info);
     
      /* Change select to use tempfile */
      if (select)
      {
	delete select->quick;
	if (select->free_cond)
	  delete select->cond;
	select->quick=0;
	select->cond=0;
      }
      else
      {
	select= new SQL_SELECT;
	select->head=table;
      }
      if (reinit_io_cache(&tempfile,READ_CACHE,0L,0,0))
	error=1; /* purecov: inspected */
      select->file=tempfile;			// Read row ptrs from this file
      if (error >= 0)
	goto err;
    }
    if (table->key_read)
      table->restore_column_maps_after_mark_index();
  }

  if (ignore)
    table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
  
  if (select && select->quick && select->quick->reset())
    goto err;
  table->file->try_semi_consistent_read(1);
  init_read_record(&info,thd,table,select,0,1);

  updated= found= 0;
  thd->count_cuted_fields= CHECK_FIELD_WARN;		/* calc cuted fields */
  thd->cuted_fields=0L;
  thd->proc_info="Updating";

  transactional_table= table->file->has_transactions();
  thd->no_trans_update.stmt= FALSE;
  thd->abort_on_warning= test(!ignore &&
                              (thd->variables.sql_mode &
                               (MODE_STRICT_TRANS_TABLES |
                                MODE_STRICT_ALL_TABLES)));
  if (table->triggers &&
      table->triggers->has_triggers(TRG_EVENT_UPDATE,
                                    TRG_ACTION_AFTER))
  {
    /*
      The table has AFTER UPDATE triggers that might access to subject 
      table and therefore might need update to be done immediately. 
      So we turn-off the batching.
    */ 
    (void) table->file->extra(HA_EXTRA_UPDATE_CANNOT_BATCH);
    will_batch= FALSE;
  }
  else
    will_batch= !table->file->start_bulk_update();

  /*
    We can use compare_record() to optimize away updates if
    the table handler is returning all columns OR if
    if all updated columns are read
  */
  can_compare_record= (!(table->file->ha_table_flags() &
                         HA_PARTIAL_COLUMN_READ) ||
                       bitmap_is_subset(table->write_set, table->read_set));

  while (!(error=info.read_record(&info)) && !thd->killed)
  {
    if (!(select && select->skip_record()))
    {
      if (table->file->was_semi_consistent_read())
        continue;  /* repeat the read of the same row if it still exists */

      store_record(table,record[1]);
      if (fill_record_n_invoke_before_triggers(thd, fields, values, 0,
                                               table->triggers,
                                               TRG_EVENT_UPDATE))
        break; /* purecov: inspected */

      found++;

      if (!can_compare_record || compare_record(table))
      {
        if ((res= table_list->view_check_option(thd, ignore)) !=
            VIEW_CHECK_OK)
        {
          found--;
          if (res == VIEW_CHECK_SKIP)
            continue;
          else if (res == VIEW_CHECK_ERROR)
          {
            error= 1;
            break;
          }
        }
        if (will_batch)
        {
          /*
            Typically a batched handler can execute the batched jobs when:
            1) When specifically told to do so
            2) When it is not a good idea to batch anymore
            3) When it is necessary to send batch for other reasons
               (One such reason is when READ's must be performed)

            1) is covered by exec_bulk_update calls.
            2) and 3) is handled by the bulk_update_row method.
            
            bulk_update_row can execute the updates including the one
            defined in the bulk_update_row or not including the row
            in the call. This is up to the handler implementation and can
            vary from call to call.

            The dup_key_found reports the number of duplicate keys found
            in those updates actually executed. It only reports those if
            the extra call with HA_EXTRA_IGNORE_DUP_KEY have been issued.
            If this hasn't been issued it returns an error code and can
            ignore this number. Thus any handler that implements batching
            for UPDATE IGNORE must also handle this extra call properly.

            If a duplicate key is found on the record included in this
            call then it should be included in the count of dup_key_found
            and error should be set to 0 (only if these errors are ignored).
          */
          error= table->file->bulk_update_row(table->record[1],
                                              table->record[0],
                                              &dup_key_found);
          limit+= dup_key_found;
          updated-= dup_key_found;
        }
        else
        {
          /* Non-batched update */
	  error= table->file->ha_update_row(table->record[1],
                                            table->record[0]);
        }
        if (!error)
	{
	  updated++;
          thd->no_trans_update.stmt= !transactional_table;

          if (table->triggers &&
              table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                                TRG_ACTION_AFTER, TRUE))
          {
            error= 1;
            break;
          }
	}
 	else if (!ignore ||
                 table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))
	{
          /*
            If (ignore && error is ignorable) we don't have to
            do anything; otherwise...
          */
          if (table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))
            thd->fatal_error(); /* Other handler errors are fatal */
	  table->file->print_error(error,MYF(0));
	  error= 1;
	  break;
	}
      }

      if (!--limit && using_limit)
      {
        /*
          We have reached end-of-file in most common situations where no
          batching has occurred and if batching was supposed to occur but
          no updates were made and finally when the batch execution was
          performed without error and without finding any duplicate keys.
          If the batched updates were performed with errors we need to
          check and if no error but duplicate key's found we need to
          continue since those are not counted for in limit.
        */
        if (will_batch &&
            ((error= table->file->exec_bulk_update(&dup_key_found)) ||
            !dup_key_found))
        {
 	  if (error)
          {
            /*
              The handler should not report error of duplicate keys if they
              are ignored. This is a requirement on batching handlers.
            */
            table->file->print_error(error,MYF(0));
            error= 1;
            break;
          }
          /*
            Either an error was found and we are ignoring errors or there
            were duplicate keys found. In both cases we need to correct
            the counters and continue the loop.
          */
          limit= dup_key_found; //limit is 0 when we get here so need to +
          updated-= dup_key_found;
        }
        else
        {
	  error= -1;				// Simulate end of file
	  break;
        }
      }
    }
    else
      table->file->unlock_row();
    thd->row_count++;
  }
  dup_key_found= 0;
  if (thd->killed && !error)
    error= 1;					// Aborted
  else if (will_batch &&
           (loc_error= table->file->exec_bulk_update(&dup_key_found)))
    /*
      An error has occurred when a batched update was performed and returned
      an error indication. It cannot be an allowed duplicate key error since
      we require the batching handler to treat this as a normal behavior.

      Otherwise we simply remove the number of duplicate keys records found
      in the batched update.
    */
  {
    thd->fatal_error();
    table->file->print_error(loc_error,MYF(0));
    error= 1;
  }
  else
    updated-= dup_key_found;
  if (will_batch)
    table->file->end_bulk_update();
  table->file->try_semi_consistent_read(0);
  end_read_record(&info);
  delete select;
  thd->proc_info= "end";
  VOID(table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY));

  /*
    Invalidate the table in the query cache if something changed.
    This must be before binlog writing and ha_autocommit_...
  */
  if (updated)
  {
    query_cache_invalidate3(thd, table_list, 1);
  }

  /*
    error < 0 means really no error at all: we processed all rows until the
    last one without error. error > 0 means an error (e.g. unique key
    violation and no IGNORE or REPLACE). error == 0 is also an error (if
    preparing the record or invoking before triggers fails). See
    ha_autocommit_or_rollback(error>=0) and DBUG_RETURN(error>=0) below.
    Sometimes we want to binlog even if we updated no rows, in case user used
    it to be sure master and slave are in same state.
  */
  if ((error < 0) || (updated && !transactional_table))
  {
    if (mysql_bin_log.is_open())
    {
      if (error < 0)
        thd->clear_error();
      if (thd->binlog_query(THD::ROW_QUERY_TYPE,
                            thd->query, thd->query_length,
                            transactional_table, FALSE) &&
          transactional_table)
      {
        error=1;				// Rollback update
      }
    }
    if (!transactional_table)
      thd->no_trans_update.all= TRUE;
  }
  free_underlaid_joins(thd, select_lex);
  if (transactional_table)
  {
    if (ha_autocommit_or_rollback(thd, error >= 0))
      error=1;
  }

  if (thd->lock)
  {
    mysql_unlock_tables(thd, thd->lock);
    thd->lock=0;
  }

  /* If LAST_INSERT_ID(X) was used, report X */
  id= thd->arg_of_last_insert_id_function ?
    thd->first_successful_insert_id_in_prev_stmt : 0;

  if (error < 0)
  {
    char buff[STRING_BUFFER_USUAL_SIZE];
    sprintf(buff, ER(ER_UPDATE_INFO), (ulong) found, (ulong) updated,
	    (ulong) thd->cuted_fields);
    thd->row_count_func=
      (thd->client_capabilities & CLIENT_FOUND_ROWS) ? found : updated;
    send_ok(thd, (ulong) thd->row_count_func, id, buff);
    DBUG_PRINT("info",("%ld records updated", (long) updated));
  }
  thd->count_cuted_fields= CHECK_FIELD_IGNORE;		/* calc cuted fields */
  thd->abort_on_warning= 0;
  DBUG_RETURN((error >= 0 || thd->net.report_error) ? 1 : 0);

err:
  delete select;
  free_underlaid_joins(thd, select_lex);
  if (table->key_read)
  {
    table->key_read=0;
    table->file->extra(HA_EXTRA_NO_KEYREAD);
  }
  thd->abort_on_warning= 0;
  DBUG_RETURN(1);
}

/*
  Prepare items in UPDATE statement

  SYNOPSIS
    mysql_prepare_update()
    thd			- thread handler
    table_list		- global/local table list
    conds		- conditions
    order_num		- number of ORDER BY list entries
    order		- ORDER BY clause list

  RETURN VALUE
    FALSE OK
    TRUE  error
*/
bool mysql_prepare_update(THD *thd, TABLE_LIST *table_list,
			 Item **conds, uint order_num, ORDER *order)
{
  Item *fake_conds= 0;
  TABLE *table= table_list->table;
  TABLE_LIST tables;
  List<Item> all_fields;
  SELECT_LEX *select_lex= &thd->lex->select_lex;
  DBUG_ENTER("mysql_prepare_update");

#ifndef NO_EMBEDDED_ACCESS_CHECKS
  table_list->grant.want_privilege= table->grant.want_privilege= 
    (SELECT_ACL & ~table->grant.privilege);
  table_list->register_want_access(SELECT_ACL);
#endif

  bzero((char*) &tables,sizeof(tables));	// For ORDER BY
  tables.table= table;
  tables.alias= table_list->alias;
  thd->lex->allow_sum_func= 0;

  if (setup_tables_and_check_access(thd, &select_lex->context, 
                                    &select_lex->top_join_list,
                                    table_list,
                                    &select_lex->leaf_tables,
                                    FALSE, UPDATE_ACL, SELECT_ACL) ||
      setup_conds(thd, table_list, select_lex->leaf_tables, conds) ||
      select_lex->setup_ref_array(thd, order_num) ||
      setup_order(thd, select_lex->ref_pointer_array,
		  table_list, all_fields, all_fields, order) ||
      setup_ftfuncs(select_lex))
    DBUG_RETURN(TRUE);

  /* Check that we are not using table that we are updating in a sub select */
  {
    TABLE_LIST *duplicate;
    if ((duplicate= unique_table(thd, table_list, table_list->next_global, 0)))
    {
      update_non_unique_table_error(table_list, "UPDATE", duplicate);
      my_error(ER_UPDATE_TABLE_USED, MYF(0), table_list->table_name);
      DBUG_RETURN(TRUE);
    }
  }
  select_lex->fix_prepare_information(thd, conds, &fake_conds);
  DBUG_RETURN(FALSE);
}


/***************************************************************************
  Update multiple tables from join 
***************************************************************************/

/*
  Get table map for list of Item_field
*/

static table_map get_table_map(List<Item> *items)
{
  List_iterator_fast<Item> item_it(*items);
  Item_field *item;
  table_map map= 0;

  while ((item= (Item_field *) item_it++)) 
    map|= item->used_tables();
  DBUG_PRINT("info", ("table_map: 0x%08lx", (long) map));
  return map;
}


/*
  make update specific preparation and checks after opening tables

  SYNOPSIS
    mysql_multi_update_prepare()
    thd         thread handler

  RETURN
    FALSE OK
    TRUE  Error
*/

bool mysql_multi_update_prepare(THD *thd)
{
  LEX *lex= thd->lex;
  TABLE_LIST *table_list= lex->query_tables;
  TABLE_LIST *tl, *leaves;
  List<Item> *fields= &lex->select_lex.item_list;
  table_map tables_for_update;
  bool update_view= 0;
  /*
    if this multi-update was converted from usual update, here is table
    counter else junk will be assigned here, but then replaced with real
    count in open_tables()
  */
  uint  table_count= lex->table_count;
  const bool using_lock_tables= thd->locked_tables != 0;
  bool original_multiupdate= (thd->lex->sql_command == SQLCOM_UPDATE_MULTI);
  bool need_reopen= FALSE;
  DBUG_ENTER("mysql_multi_update_prepare");

  /* following need for prepared statements, to run next time multi-update */
  thd->lex->sql_command= SQLCOM_UPDATE_MULTI;

reopen_tables:

  /* open tables and create derived ones, but do not lock and fill them */
  if (((original_multiupdate || need_reopen) &&
       open_tables(thd, &table_list, &table_count, 0)) ||
      mysql_handle_derived(lex, &mysql_derived_prepare))
    DBUG_RETURN(TRUE);
  /*
    setup_tables() need for VIEWs. JOIN::prepare() will call setup_tables()
    second time, but this call will do nothing (there are check for second
    call in setup_tables()).
  */

  if (setup_tables_and_check_access(thd, &lex->select_lex.context,
                                    &lex->select_lex.top_join_list,
                                    table_list,
                                    &lex->select_lex.leaf_tables, FALSE,
                                    UPDATE_ACL, SELECT_ACL))
    DBUG_RETURN(TRUE);

  if (setup_fields_with_no_wrap(thd, 0, *fields, MARK_COLUMNS_WRITE, 0, 0))
    DBUG_RETURN(TRUE);

  for (tl= table_list; tl ; tl= tl->next_local)
  {
    if (tl->view)
    {
      update_view= 1;
      break;
    }
  }

  if (update_view && check_fields(thd, *fields))
  {
    DBUG_RETURN(TRUE);
  }

  tables_for_update= get_table_map(fields);

  /*
    Setup timestamp handling and locking mode
  */
  leaves= lex->select_lex.leaf_tables;
  for (tl= leaves; tl; tl= tl->next_leaf)
  {
    TABLE *table= tl->table;
    /* Only set timestamp column if this is not modified */
    if (table->timestamp_field &&
        bitmap_is_set(table->write_set,
                      table->timestamp_field->field_index))
      table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;

    /* if table will be updated then check that it is unique */
    if (table->map & tables_for_update)
    {
      if (!tl->updatable || check_key_in_view(thd, tl))
      {
        my_error(ER_NON_UPDATABLE_TABLE, MYF(0), tl->alias, "UPDATE");
        DBUG_RETURN(TRUE);
      }

      table->mark_columns_needed_for_update();
      DBUG_PRINT("info",("setting table `%s` for update", tl->alias));
      /*
        If table will be updated we should not downgrade lock for it and
        leave it as is.
      */
    }
    else
    {
      DBUG_PRINT("info",("setting table `%s` for read-only", tl->alias));
      /*
        If we are using the binary log, we need TL_READ_NO_INSERT to get
        correct order of statements. Otherwise, we use a TL_READ lock to
        improve performance.
      */
      tl->lock_type= using_update_log ? TL_READ_NO_INSERT : TL_READ;
      tl->updating= 0;
      /* Update TABLE::lock_type accordingly. */
      if (!tl->placeholder() && !using_lock_tables)
        tl->table->reginfo.lock_type= tl->lock_type;
    }
  }
  for (tl= table_list; tl; tl= tl->next_local)
  {
    /* Check access privileges for table */
    if (!tl->derived)
    {
      uint want_privilege= tl->updating ? UPDATE_ACL : SELECT_ACL;
      if (check_access(thd, want_privilege,
                       tl->db, &tl->grant.privilege, 0, 0, 
                       test(tl->schema_table)) ||
          (grant_option && check_grant(thd, want_privilege, tl, 0, 1, 0)))
        DBUG_RETURN(TRUE);
    }
  }

  /* check single table update for view compound from several tables */
  for (tl= table_list; tl; tl= tl->next_local)
  {
    if (tl->effective_algorithm == VIEW_ALGORITHM_MERGE)
    {
      TABLE_LIST *for_update= 0;
      if (tl->check_single_table(&for_update, tables_for_update, tl))
      {
	my_error(ER_VIEW_MULTIUPDATE, MYF(0),
		 tl->view_db.str, tl->view_name.str);
	DBUG_RETURN(-1);
      }
    }
  }

  /* now lock and fill tables */
  if (lock_tables(thd, table_list, table_count, &need_reopen))
  {
    if (!need_reopen)
      DBUG_RETURN(TRUE);

    /*
      We have to reopen tables since some of them were altered or dropped
      during lock_tables() or something was done with their triggers.
      Let us do some cleanups to be able do setup_table() and setup_fields()
      once again.
    */
    List_iterator_fast<Item> it(*fields);
    Item *item;
    while ((item= it++))
      item->cleanup();

    /* We have to cleanup translation tables of views. */
    for (TABLE_LIST *tbl= table_list; tbl; tbl= tbl->next_global)
      tbl->cleanup_items();

    close_tables_for_reopen(thd, &table_list);
    goto reopen_tables;
  }

  /*
    Check that we are not using table that we are updating, but we should
    skip all tables of UPDATE SELECT itself
  */
  lex->select_lex.exclude_from_table_unique_test= TRUE;
  /* We only need SELECT privilege for columns in the values list */
  for (tl= leaves; tl; tl= tl->next_leaf)
  {
    TABLE *table= tl->table;
    TABLE_LIST *tlist;
    if (!(tlist= tl->top_table())->derived)
    {
      tlist->grant.want_privilege=
        (SELECT_ACL & ~tlist->grant.privilege);
      table->grant.want_privilege= (SELECT_ACL & ~table->grant.privilege);
    }
    DBUG_PRINT("info", ("table: %s  want_privilege: %u", tl->alias,
                        (uint) table->grant.want_privilege));
    if (tl->lock_type != TL_READ &&
        tl->lock_type != TL_READ_NO_INSERT)
    {
      TABLE_LIST *duplicate;
      if ((duplicate= unique_table(thd, tl, table_list, 0)))
      {
        update_non_unique_table_error(table_list, "UPDATE", duplicate);
        DBUG_RETURN(TRUE);
      }
    }
  }
  /*
    Set exclude_from_table_unique_test value back to FALSE. It is needed for
    further check in multi_update::prepare whether to use record cache.
  */
  lex->select_lex.exclude_from_table_unique_test= FALSE;
 
  if (thd->fill_derived_tables() &&
      mysql_handle_derived(lex, &mysql_derived_filling))
    DBUG_RETURN(TRUE);

  DBUG_RETURN (FALSE);
}


/*
  Setup multi-update handling and call SELECT to do the join
*/

bool mysql_multi_update(THD *thd,
                        TABLE_LIST *table_list,
                        List<Item> *fields,
                        List<Item> *values,
                        COND *conds,
                        ulonglong options,
                        enum enum_duplicates handle_duplicates, bool ignore,
                        SELECT_LEX_UNIT *unit, SELECT_LEX *select_lex)
{
  multi_update *result;
  DBUG_ENTER("mysql_multi_update");

  if (!(result= new multi_update(table_list,
				 thd->lex->select_lex.leaf_tables,
				 fields, values,
				 handle_duplicates, ignore)))
    DBUG_RETURN(TRUE);

  thd->no_trans_update.stmt= FALSE;
  thd->abort_on_warning= test(thd->variables.sql_mode &
                              (MODE_STRICT_TRANS_TABLES |
                               MODE_STRICT_ALL_TABLES));

  List<Item> total_list;
  (void) mysql_select(thd, &select_lex->ref_pointer_array,
                      table_list, select_lex->with_wild,
                      total_list,
                      conds, 0, (ORDER *) NULL, (ORDER *)NULL, (Item *) NULL,
                      (ORDER *)NULL,
                      options | SELECT_NO_JOIN_CACHE | SELECT_NO_UNLOCK |
                      OPTION_SETUP_TABLES_DONE,
                      result, unit, select_lex);
  delete result;
  thd->abort_on_warning= 0;
  DBUG_RETURN(FALSE);
}


multi_update::multi_update(TABLE_LIST *table_list,
			   TABLE_LIST *leaves_list,
			   List<Item> *field_list, List<Item> *value_list,
			   enum enum_duplicates handle_duplicates_arg,
                           bool ignore_arg)
  :all_tables(table_list), leaves(leaves_list), update_tables(0),
   tmp_tables(0), updated(0), found(0), fields(field_list),
   values(value_list), table_count(0), copy_field(0),
   handle_duplicates(handle_duplicates_arg), do_update(1), trans_safe(0),
   transactional_tables(1), ignore(ignore_arg)
{}


/*
  Connect fields with tables and create list of tables that are updated
*/

int multi_update::prepare(List<Item> &not_used_values,
			  SELECT_LEX_UNIT *lex_unit)
{
  TABLE_LIST *table_ref;
  SQL_LIST update;
  table_map tables_to_update;
  Item_field *item;
  List_iterator_fast<Item> field_it(*fields);
  List_iterator_fast<Item> value_it(*values);
  uint i, max_fields;
  uint leaf_table_count= 0;
  DBUG_ENTER("multi_update::prepare");

  thd->count_cuted_fields= CHECK_FIELD_WARN;
  thd->cuted_fields=0L;
  thd->proc_info="updating main table";

  tables_to_update= get_table_map(fields);

  if (!tables_to_update)
  {
    my_message(ER_NO_TABLES_USED, ER(ER_NO_TABLES_USED), MYF(0));
    DBUG_RETURN(1);
  }

  /*
    We have to check values after setup_tables to get covering_keys right in
    reference tables
  */

  if (setup_fields(thd, 0, *values, MARK_COLUMNS_READ, 0, 0))
    DBUG_RETURN(1);

  /*
    Save tables beeing updated in update_tables
    update_table->shared is position for table
    Don't use key read on tables that are updated
  */

  update.empty();
  for (table_ref= leaves; table_ref; table_ref= table_ref->next_leaf)
  {
    /* TODO: add support of view of join support */
    TABLE *table=table_ref->table;
    leaf_table_count++;
    if (tables_to_update & table->map)
    {
      TABLE_LIST *tl= (TABLE_LIST*) thd->memdup((char*) table_ref,
						sizeof(*tl));
      if (!tl)
	DBUG_RETURN(1);
      update.link_in_list((uchar*) tl, (uchar**) &tl->next_local);
      tl->shared= table_count++;
      table->no_keyread=1;
      table->covering_keys.clear_all();
      table->pos_in_table_list= tl;
      if (table->triggers &&
          table->triggers->has_triggers(TRG_EVENT_UPDATE,
                                        TRG_ACTION_AFTER))
      {
	/*
           The table has AFTER UPDATE triggers that might access to subject 
           table and therefore might need update to be done immediately. 
           So we turn-off the batching.
	*/ 
	(void) table->file->extra(HA_EXTRA_UPDATE_CANNOT_BATCH);
      }
    }
  }


  table_count=  update.elements;
  update_tables= (TABLE_LIST*) update.first;

  tmp_tables = (TABLE**) thd->calloc(sizeof(TABLE *) * table_count);
  tmp_table_param = (TMP_TABLE_PARAM*) thd->calloc(sizeof(TMP_TABLE_PARAM) *
						   table_count);
  fields_for_table= (List_item **) thd->alloc(sizeof(List_item *) *
					      table_count);
  values_for_table= (List_item **) thd->alloc(sizeof(List_item *) *
					      table_count);
  if (thd->is_fatal_error)
    DBUG_RETURN(1);
  for (i=0 ; i < table_count ; i++)
  {
    fields_for_table[i]= new List_item;
    values_for_table[i]= new List_item;
  }
  if (thd->is_fatal_error)
    DBUG_RETURN(1);

  /* Split fields into fields_for_table[] and values_by_table[] */

  while ((item= (Item_field *) field_it++))
  {
    Item *value= value_it++;
    uint offset= item->field->table->pos_in_table_list->shared;
    fields_for_table[offset]->push_back(item);
    values_for_table[offset]->push_back(value);
  }
  if (thd->is_fatal_error)
    DBUG_RETURN(1);

  /* Allocate copy fields */
  max_fields=0;
  for (i=0 ; i < table_count ; i++)
    set_if_bigger(max_fields, fields_for_table[i]->elements + leaf_table_count);
  copy_field= new Copy_field[max_fields];
  DBUG_RETURN(thd->is_fatal_error != 0);
}


/*
  Check if table is safe to update on fly

  SYNOPSIS
    safe_update_on_fly()
    thd                 Thread handler
    join_tab            How table is used in join
    all_tables          List of tables

  NOTES
    We can update the first table in join on the fly if we know that
    a row in this table will never be read twice. This is true under
    the following conditions:

    - We are doing a table scan and the data is in a separate file (MyISAM) or
      if we don't update a clustered key.

    - We are doing a range scan and we don't update the scan key or
      the primary key for a clustered table handler.

    - Table is not joined to itself.

    This function gets information about fields to be updated from
    the TABLE::write_set bitmap.

  WARNING
    This code is a bit dependent of how make_join_readinfo() works.

  RETURN
    0		Not safe to update
    1		Safe to update
*/

static bool safe_update_on_fly(THD *thd, JOIN_TAB *join_tab,
                               TABLE_LIST *table_ref, TABLE_LIST *all_tables)
{
  TABLE *table= join_tab->table;
  if (unique_table(thd, table_ref, all_tables, 0))
    return 0;
  switch (join_tab->type) {
  case JT_SYSTEM:
  case JT_CONST:
  case JT_EQ_REF:
    return TRUE;				// At most one matching row
  case JT_REF:
  case JT_REF_OR_NULL:
    return !is_key_used(table, join_tab->ref.key, table->write_set);
  case JT_ALL:
    /* If range search on index */
    if (join_tab->quick)
      return !join_tab->quick->is_keys_used(table->write_set);
    /* If scanning in clustered key */
    if ((table->file->ha_table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&
	table->s->primary_key < MAX_KEY)
      return !is_key_used(table, table->s->primary_key, table->write_set);
    return TRUE;
  default:
    break;					// Avoid compler warning
  }
  return FALSE;

}


/*
  Initialize table for multi table

  IMPLEMENTATION
    - Update first table in join on the fly, if possible
    - Create temporary tables to store changed values for all other tables
      that are updated (and main_table if the above doesn't hold).
*/

bool
multi_update::initialize_tables(JOIN *join)
{
  TABLE_LIST *table_ref;
  DBUG_ENTER("initialize_tables");

  if ((thd->options & OPTION_SAFE_UPDATES) && error_if_full_join(join))
    DBUG_RETURN(1);
  main_table=join->join_tab->table;
  trans_safe= transactional_tables= main_table->file->has_transactions();
  table_to_update= 0;

  /* Any update has at least one pair (field, value) */
  DBUG_ASSERT(fields->elements);
  /*
   Only one table may be modified by UPDATE of an updatable view.
   For an updatable view first_table_for_update indicates this
   table.
   For a regular multi-update it refers to some updated table.
  */ 
  TABLE *first_table_for_update= ((Item_field *) fields->head())->field->table;

  /* Create a temporary table for keys to all tables, except main table */
  for (table_ref= update_tables; table_ref; table_ref= table_ref->next_local)
  {
    TABLE *table=table_ref->table;
    uint cnt= table_ref->shared;
    List<Item> temp_fields;
    ORDER     group;
    TMP_TABLE_PARAM *tmp_param;

    table->mark_columns_needed_for_update();
    if (ignore)
      table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
    if (table == main_table)			// First table in join
    {
      if (safe_update_on_fly(thd, join->join_tab, table_ref, all_tables))
      {
	table_to_update= main_table;		// Update table on the fly
	continue;
      }
    }
    table->prepare_for_position();

    if (table == first_table_for_update && table_ref->check_option)
    {
      table_map unupdated_tables= table_ref->check_option->used_tables() &
                                  ~first_table_for_update->map;
      for (TABLE_LIST *tbl_ref =leaves;
           unupdated_tables && tbl_ref;
           tbl_ref= tbl_ref->next_leaf)
      {
        if (unupdated_tables & tbl_ref->table->map)
          unupdated_tables&= ~tbl_ref->table->map;
        else
          continue;
        if (unupdated_check_opt_tables.push_back(tbl_ref->table))
          DBUG_RETURN(1);
      }
    }

    tmp_param= tmp_table_param+cnt;

    /*
      Create a temporary table to store all fields that are changed for this
      table. The first field in the temporary table is a pointer to the
      original row so that we can find and update it. For the updatable
      VIEW a few following fields are rowids of tables used in the CHECK
      OPTION condition.
    */

    List_iterator_fast<TABLE> tbl_it(unupdated_check_opt_tables);
    TABLE *tbl= table;
    do
    {
      Field_string *field= new Field_string(tbl->file->ref_length, 0,
                                            tbl->alias, &my_charset_bin);
      if (!field)
        DBUG_RETURN(1);
      field->init(tbl);
      /*
        The field will be converted to varstring when creating tmp table if
        table to be updated was created by mysql 4.1. Deny this.
      */
      field->can_alter_field_type= 0;
      Item_field *ifield= new Item_field((Field *) field);
      if (!ifield)
         DBUG_RETURN(1);
      ifield->maybe_null= 0;
      if (temp_fields.push_back(ifield))
        DBUG_RETURN(1);
    } while ((tbl= tbl_it++));

    temp_fields.concat(fields_for_table[cnt]);

    /* Make an unique key over the first field to avoid duplicated updates */
    bzero((char*) &group, sizeof(group));
    group.asc= 1;
    group.item= (Item**) temp_fields.head_ref();

    tmp_param->quick_group=1;
    tmp_param->field_count=temp_fields.elements;
    tmp_param->group_parts=1;
    tmp_param->group_length= table->file->ref_length;
    if (!(tmp_tables[cnt]=create_tmp_table(thd,
					   tmp_param,
					   temp_fields,
					   (ORDER*) &group, 0, 0,
					   TMP_TABLE_ALL_COLUMNS,
					   HA_POS_ERROR,
					   (char *) "")))
      DBUG_RETURN(1);
    tmp_tables[cnt]->file->extra(HA_EXTRA_WRITE_CACHE);
  }
  DBUG_RETURN(0);
}


multi_update::~multi_update()
{
  TABLE_LIST *table;
  for (table= update_tables ; table; table= table->next_local)
  {
    table->table->no_keyread= table->table->no_cache= 0;
    if (ignore)
      table->table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);
  }

  if (tmp_tables)
  {
    for (uint cnt = 0; cnt < table_count; cnt++)
    {
      if (tmp_tables[cnt])
      {
	free_tmp_table(thd, tmp_tables[cnt]);
	tmp_table_param[cnt].cleanup();
      }
    }
  }
  if (copy_field)
    delete [] copy_field;
  thd->count_cuted_fields= CHECK_FIELD_IGNORE;		// Restore this setting
  if (!trans_safe)
    thd->no_trans_update.all= TRUE;
}


bool multi_update::send_data(List<Item> &not_used_values)
{
  TABLE_LIST *cur_table;
  DBUG_ENTER("multi_update::send_data");

  for (cur_table= update_tables; cur_table; cur_table= cur_table->next_local)
  {
    TABLE *table= cur_table->table;
    uint offset= cur_table->shared;
    /*
      Check if we are using outer join and we didn't find the row
      or if we have already updated this row in the previous call to this
      function.

      The same row may be presented here several times in a join of type
      UPDATE t1 FROM t1,t2 SET t1.a=t2.a

      In this case we will do the update for the first found row combination.
      The join algorithm guarantees that we will not find the a row in
      t1 several times.
    */
    if (table->status & (STATUS_NULL_ROW | STATUS_UPDATED))
      continue;

    /*
      We can use compare_record() to optimize away updates if
      the table handler is returning all columns OR if
      if all updated columns are read
    */
    if (table == table_to_update)
    {
      bool can_compare_record;
      can_compare_record= (!(table->file->ha_table_flags() &
                             HA_PARTIAL_COLUMN_READ) ||
                           bitmap_is_subset(table->write_set,
                                            table->read_set));
      table->status|= STATUS_UPDATED;
      store_record(table,record[1]);
      if (fill_record_n_invoke_before_triggers(thd, *fields_for_table[offset],
                                               *values_for_table[offset], 0,
                                               table->triggers,
                                               TRG_EVENT_UPDATE))
	DBUG_RETURN(1);

      found++;
      if (!can_compare_record || compare_record(table))
      {
	int error;
        if ((error= cur_table->view_check_option(thd, ignore)) !=
            VIEW_CHECK_OK)
        {
          found--;
          if (error == VIEW_CHECK_SKIP)
            continue;
          else if (error == VIEW_CHECK_ERROR)
            DBUG_RETURN(1);
        }
        if (!updated++)
        {
          /*
            Inform the main table that we are going to update the table even
            while we may be scanning it.  This will flush the read cache
            if it's used.
          */
          main_table->file->extra(HA_EXTRA_PREPARE_FOR_UPDATE);
        }
        if ((error=table->file->ha_update_row(table->record[1],
                                              table->record[0])))
        {
          updated--;
          if (!ignore ||
              table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))
          {
            /*
              If (ignore && error == is ignorable) we don't have to
              do anything; otherwise...
            */
            if (table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))
              thd->fatal_error(); /* Other handler errors are fatal */
            table->file->print_error(error,MYF(0));
            DBUG_RETURN(1);
          }
        }
        else
        {
          if (!table->file->has_transactions())
            thd->no_trans_update.stmt= TRUE;
          if (table->triggers &&
              table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                                TRG_ACTION_AFTER, TRUE))
            DBUG_RETURN(1);
        }
      }
    }
    else
    {
      int error;
      TABLE *tmp_table= tmp_tables[offset];
      /*
       For updatable VIEW store rowid of the updated table and
       rowids of tables used in the CHECK OPTION condition.
      */
      uint field_num= 0;
      List_iterator_fast<TABLE> tbl_it(unupdated_check_opt_tables);
      TABLE *tbl= table;
      do
      {
        tbl->file->position(tbl->record[0]);
        memcpy((char*) tmp_table->field[field_num]->ptr,
               (char*) tbl->file->ref, tbl->file->ref_length);
        field_num++;
      } while ((tbl= tbl_it++));

      /* Store regular updated fields in the row. */
      fill_record(thd,
                  tmp_table->field + 1 + unupdated_check_opt_tables.elements,
                  *values_for_table[offset], 1);

      /* Write row, ignoring duplicated updates to a row */
      error= tmp_table->file->ha_write_row(tmp_table->record[0]);
      if (error != HA_ERR_FOUND_DUPP_KEY && error != HA_ERR_FOUND_DUPP_UNIQUE)
      {
        if (error &&
            create_myisam_from_heap(thd, tmp_table,
                                    tmp_table_param + offset, error, 1))
        {
          do_update= 0;
          DBUG_RETURN(1);			// Not a table_is_full error
        }
        found++;
      }
    }
  }
  DBUG_RETURN(0);
}


void multi_update::send_error(uint errcode,const char *err)
{
  /* First send error what ever it is ... */
  my_error(errcode, MYF(0), err);

  /* If nothing updated return */
  if (!updated)
    return;

  /* Something already updated so we have to invalidate cache */
  query_cache_invalidate3(thd, update_tables, 1);

  /*
    If all tables that has been updated are trans safe then just do rollback.
    If not attempt to do remaining updates.
  */

  if (trans_safe)
    ha_rollback_stmt(thd);
  else if (do_update && table_count > 1)
  {
    /* Add warning here */
    VOID(do_updates(0));
  }
}


int multi_update::do_updates(bool from_send_error)
{
  TABLE_LIST *cur_table;
  int local_error= 0;
  ha_rows org_updated;
  TABLE *table, *tmp_table;
  List_iterator_fast<TABLE> check_opt_it(unupdated_check_opt_tables);
  DBUG_ENTER("do_updates");

  do_update= 0;					// Don't retry this function
  if (!found)
    DBUG_RETURN(0);
  for (cur_table= update_tables; cur_table; cur_table= cur_table->next_local)
  {
    bool can_compare_record;
    uint offset= cur_table->shared;

    table = cur_table->table;
    if (table == table_to_update)
      continue;					// Already updated
    org_updated= updated;
    tmp_table= tmp_tables[cur_table->shared];
    tmp_table->file->extra(HA_EXTRA_CACHE);	// Change to read cache
    (void) table->file->ha_rnd_init(0);
    table->file->extra(HA_EXTRA_NO_CACHE);

    check_opt_it.rewind();
    while(TABLE *tbl= check_opt_it++)
    {
      if (tbl->file->ha_rnd_init(1))
        goto err;
      tbl->file->extra(HA_EXTRA_CACHE);
    }

    /*
      Setup copy functions to copy fields from temporary table
    */
    List_iterator_fast<Item> field_it(*fields_for_table[offset]);
    Field **field= tmp_table->field + 
                   1 + unupdated_check_opt_tables.elements; // Skip row pointers
    Copy_field *copy_field_ptr= copy_field, *copy_field_end;
    for ( ; *field ; field++)
    {
      Item_field *item= (Item_field* ) field_it++;
      (copy_field_ptr++)->set(item->field, *field, 0);
    }
    copy_field_end=copy_field_ptr;

    if ((local_error = tmp_table->file->ha_rnd_init(1)))
      goto err;

    can_compare_record= (!(table->file->ha_table_flags() &
                           HA_PARTIAL_COLUMN_READ) ||
                         bitmap_is_subset(table->write_set,
                                          table->read_set));

    for (;;)
    {
      if (thd->killed && trans_safe)
	goto err;
      if ((local_error=tmp_table->file->rnd_next(tmp_table->record[0])))
      {
	if (local_error == HA_ERR_END_OF_FILE)
	  break;
	if (local_error == HA_ERR_RECORD_DELETED)
	  continue;				// May happen on dup key
	goto err;
      }

      /* call rnd_pos() using rowids from temporary table */
      check_opt_it.rewind();
      TABLE *tbl= table;
      uint field_num= 0;
      do
      {
        if((local_error=
              tbl->file->rnd_pos(tbl->record[0],
                                (uchar *) tmp_table->field[field_num]->ptr)))
          goto err;
        field_num++;
      } while((tbl= check_opt_it++));

      table->status|= STATUS_UPDATED;
      store_record(table,record[1]);

      /* Copy data from temporary table to current table */
      for (copy_field_ptr=copy_field;
	   copy_field_ptr != copy_field_end;
	   copy_field_ptr++)
	(*copy_field_ptr->do_copy)(copy_field_ptr);

      if (table->triggers &&
          table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                            TRG_ACTION_BEFORE, TRUE))
        goto err2;

      if (!can_compare_record || compare_record(table))
      {
        int error;
        if ((error= cur_table->view_check_option(thd, ignore)) !=
            VIEW_CHECK_OK)
        {
          if (error == VIEW_CHECK_SKIP)
            continue;
          else if (error == VIEW_CHECK_ERROR)
            goto err;
        }
	if ((local_error=table->file->ha_update_row(table->record[1],
						    table->record[0])))
	{
	  if (!ignore ||
              table->file->is_fatal_error(local_error, HA_CHECK_DUP_KEY))
	    goto err;
	}
	updated++;

        if (table->triggers &&
            table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                              TRG_ACTION_AFTER, TRUE))
          goto err2;
      }
    }

    if (updated != org_updated)
    {
      if (table->file->has_transactions())
	transactional_tables= 1;
      else
	trans_safe= 0;				// Can't do safe rollback
    }
    (void) table->file->ha_rnd_end();
    (void) tmp_table->file->ha_rnd_end();
    check_opt_it.rewind();
    while (TABLE *tbl= check_opt_it++)
        tbl->file->ha_rnd_end();

  }
  DBUG_RETURN(0);

err:
  if (!from_send_error)
  {
    thd->fatal_error();
    table->file->print_error(local_error,MYF(0));
  }

err2:
  (void) table->file->ha_rnd_end();
  (void) tmp_table->file->ha_rnd_end();
  check_opt_it.rewind();
  while (TABLE *tbl= check_opt_it++)
      tbl->file->ha_rnd_end();

  if (updated != org_updated)
  {
    if (table->file->has_transactions())
      transactional_tables= 1;
    else
      trans_safe= 0;
  }
  DBUG_RETURN(1);
}


/* out: 1 if error, 0 if success */

bool multi_update::send_eof()
{
  char buff[STRING_BUFFER_USUAL_SIZE];
  ulonglong id;
  thd->proc_info="updating reference tables";

  /* Does updates for the last n - 1 tables, returns 0 if ok */
  int local_error = (table_count) ? do_updates(0) : 0;
  thd->proc_info= "end";

  /* We must invalidate the query cache before binlog writing and
  ha_autocommit_... */

  if (updated)
  {
    query_cache_invalidate3(thd, update_tables, 1);
  }

  /*
    Write the SQL statement to the binlog if we updated
    rows and we succeeded or if we updated some non
    transactional tables.
  */

  if ((local_error == 0) || (updated && !trans_safe))
  {
    if (mysql_bin_log.is_open())
    {
      if (local_error == 0)
        thd->clear_error();
      if (thd->binlog_query(THD::ROW_QUERY_TYPE,
                            thd->query, thd->query_length,
                            transactional_tables, FALSE) &&
          trans_safe)
      {
	local_error= 1;				// Rollback update
      }
    }
    if (!transactional_tables)
     thd->no_trans_update.all= TRUE;
  }

  if (transactional_tables)
  {
    if (ha_autocommit_or_rollback(thd, local_error != 0))
      local_error=1;
  }

  if (local_error > 0) // if the above log write did not fail ...
  {
    /* Safety: If we haven't got an error before (should not happen) */
    my_message(ER_UNKNOWN_ERROR, "An error occured in multi-table update",
	       MYF(0));
    return TRUE;
  }

  id= thd->arg_of_last_insert_id_function ?
    thd->first_successful_insert_id_in_prev_stmt : 0;
  sprintf(buff, ER(ER_UPDATE_INFO), (ulong) found, (ulong) updated,
	  (ulong) thd->cuted_fields);
  thd->row_count_func=
    (thd->client_capabilities & CLIENT_FOUND_ROWS) ? found : updated;
  ::send_ok(thd, (ulong) thd->row_count_func, id, buff);
  return FALSE;
}