mariadb/sql/sql_update.cc

/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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"

static bool safe_update_on_fly(JOIN_TAB *join_tab, List<Item> *fields);

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

static bool compare_record(TABLE *table, query_id_t query_id)
{
  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 ((*ptr)->query_id == query_id &&
	(*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;
  Name_resolution_context *context= &thd->lex->select_lex.context;

  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;
  bool		can_compare_record;
  int           res;
  int		error;
  uint		used_index= MAX_KEY;
  bool          need_sort= TRUE;
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  uint		want_privilege;
#endif
  uint          table_count= 0;
  query_id_t	query_id=thd->query_id, timestamp_query_id;
  ha_rows	updated, found;
  key_map	old_used_keys;
  TABLE		*table;
  SQL_SELECT	*select;
  READ_RECORD	info;
  SELECT_LEX    *select_lex= &thd->lex->select_lex;
  bool need_reopen;
  DBUG_ENTER("mysql_update");

  LINT_INIT(timestamp_query_id);

  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;
  table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

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

#ifndef NO_EMBEDDED_ACCESS_CHECKS
  /* TABLE_LIST contain right privilages request */
  want_privilege= table_list->grant.want_privilege;
#endif
  if (mysql_prepare_update(thd, table_list, &conds, order_num, order))
    DBUG_RETURN(1);

  old_used_keys= table->used_keys;		// Keys used in WHERE
  /*
    Change the query_id for the timestamp column so that we can
    check if this is modified directly
  */
  if (table->timestamp_field)
  {
    timestamp_query_id=table->timestamp_field->query_id;
    table->timestamp_field->query_id=thd->query_id-1;
  }

  /* 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, 1, 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 (table->timestamp_field->query_id == thd->query_id)
      table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;
    else
      table->timestamp_field->query_id=timestamp_query_id;
  }

#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, 1, 0, 0))
  {
    free_underlaid_joins(thd, select_lex);
    DBUG_RETURN(1);				/* purecov: inspected */
  }

  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->used_keys.clear_all();
  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);
  /* 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(&fields));
  }
  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, fields);
  }

  if (used_key_is_modified || order)
  {
    /*
      We can't update table directly;  We must first search after all
      matching rows before updating the table!
    */
    table->file->extra(HA_EXTRA_RETRIEVE_ALL_COLS);
    if (used_index < MAX_KEY && old_used_keys.is_set(used_index))
    {
      table->key_read=1;
      table->file->extra(HA_EXTRA_KEYREAD);
    }

    /* note: can actually avoid sorting below.. */
    if (order && (need_sort || used_key_is_modified))
    {
      /*
	Doing an ORDER BY;  Let filesort find and sort the rows we are going
	to update
      */
      uint         length;
      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,
						&examined_rows))
          == HA_POS_ERROR)
      {
	free_io_cache(table);
	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;

      /*
        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()))
	{
	  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;
      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->key_read=0;
      table->file->extra(HA_EXTRA_NO_KEYREAD);
    }
  }

  if (ignore)
    table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
  
  if (select && select->quick && select->quick->reset())
        goto err;
  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";
  query_id=thd->query_id;

  transactional_table= table->file->has_transactions();
  thd->no_trans_update= 0;
  thd->abort_on_warning= test(!ignore &&
                              (thd->variables.sql_mode &
                               (MODE_STRICT_TRANS_TABLES |
                                MODE_STRICT_ALL_TABLES)));

  if (table->triggers)
    table->triggers->mark_fields_used(thd, TRG_EVENT_UPDATE);

  /*
    We can use compare_record() to optimize away updates if
    the table handler is returning all columns
  */
  can_compare_record= !(table->file->table_flags() &
                        HA_PARTIAL_COLUMN_READ);
  while (!(error=info.read_record(&info)) && !thd->killed)
  {
    if (!(select && select->skip_record()))
    {
      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, query_id))
      {
        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 (!(error=table->file->update_row((byte*) table->record[1],
					    (byte*) table->record[0])))
	{
	  updated++;
          thd->no_trans_update= !transactional_table;

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

      if (!--limit && using_limit)
      {
	error= -1;				// Simulate end of file
	break;
      }
    }
    else
      table->file->unlock_row();
    thd->row_count++;
  }
  if (thd->killed && !error)
    error= 1;					// Aborted
  end_read_record(&info);
  free_io_cache(table);				// If ORDER BY
  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();
      Query_log_event qinfo(thd, thd->query, thd->query_length,
			    transactional_table, FALSE);
      if (mysql_bin_log.write(&qinfo) && transactional_table)
	error=1;				// Rollback update
    }
    if (!transactional_table)
      thd->options|=OPTION_STATUS_NO_TRANS_UPDATE;
  }
  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 (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,
	    thd->insert_id_used ? thd->last_insert_id : 0L,buff);
    DBUG_PRINT("info",("%ld records updated", (long) updated));
  }
  thd->count_cuted_fields= CHECK_FIELD_IGNORE;		/* calc cuted fields */
  thd->abort_on_warning= 0;
  free_io_cache(table);
  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, conds, 
                                    &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)))
    {
      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.where,
                                    &lex->select_lex.leaf_tables, FALSE,
                                    UPDATE_ACL, SELECT_ACL))
    DBUG_RETURN(TRUE);

  if (setup_fields_with_no_wrap(thd, 0, *fields, 1, 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 &&
        table->timestamp_field->query_id == thd->query_id)
      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);
      }

      if (table->triggers)
        table->triggers->mark_fields_used(thd, TRG_EVENT_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() && !tl->schema_table && !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)))
      {
        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= 0;
  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;
  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 used_keys right in
    reference tables
  */

  if (setup_fields(thd, 0, *values, 1, 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;
    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((byte*) tl, (byte**) &tl->next_local);
      tl->shared= table_count++;
      table->no_keyread=1;
      table->used_keys.clear_all();
      table->pos_in_table_list= tl;
    }
  }


  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);
  copy_field= new Copy_field[max_fields];

  /*
    Mark all copies of tables that are updates to ensure that
    init_read_record() will not try to enable a cache on them

    The problem is that for queries like

    UPDATE t1, t1 AS t2 SET t1.b=t2.c WHERE t1.a=t2.a;

    the row buffer may contain things that doesn't match what is on disk
    which will cause an error when reading a row.
    (This issue is mostly relevent for MyISAM tables)
  */
  for (table_ref= leaves;  table_ref; table_ref= table_ref->next_leaf)
  {
    TABLE *table=table_ref->table;
    if ((tables_to_update & table->map) &&
        unique_table(thd, table_ref, update_tables))
      table->no_cache= 1;			// Disable row cache
  }
  DBUG_RETURN(thd->is_fatal_error != 0);
}


/*
  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;

  /* 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;
    Item_field *ifield;
    List<Item> temp_fields= *fields_for_table[cnt];
    ORDER     group;

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

    TMP_TABLE_PARAM *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
    */

    /* ok to be on stack as this is not referenced outside of this func */
    Field_string offset(table->file->ref_length, 0, "offset",
			table, &my_charset_bin);
    /*
      The field will be converted to varstring when creating tmp table if
      table to be updated was created by mysql 4.1. Deny this.
    */
    offset.can_alter_field_type= 0;
    if (!(ifield= new Item_field(((Field *) &offset))))
      DBUG_RETURN(1);
    ifield->maybe_null= 0;
    if (temp_fields.push_front(ifield))
      DBUG_RETURN(1);

    /* 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);
}

/*
  Check if table is safe to update on fly

  SYNOPSIS
    safe_update_on_fly
    join_tab		How table is used in join
    fields		Fields that are updated

  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.

    When checking for above cases we also should take into account that
    BEFORE UPDATE trigger potentially may change value of any field in row
    being updated.

  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(JOIN_TAB *join_tab, List<Item> *fields)
{
  TABLE *table= join_tab->table;
  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, *fields);
  case JT_ALL:
    /* If range search on index */
    if (join_tab->quick)
      return !join_tab->quick->is_keys_used(fields);
    /* If scanning in clustered key */
    if ((table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&
	table->s->primary_key < MAX_KEY)
      return !is_key_used(table, table->s->primary_key, *fields);
    return TRUE;
  default:
    break;					// Avoid compler warning
  }
  return FALSE;
}


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->options|=OPTION_STATUS_NO_TRANS_UPDATE;
}


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;
    /*
      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;

    uint offset= cur_table->shared;
    table->file->position(table->record[0]);
    /*
      We can use compare_record() to optimize away updates if
      the table handler is returning all columns
    */
    if (table == table_to_update)
    {
      bool can_compare_record;
      can_compare_record= !(table->file->table_flags() &
                            HA_PARTIAL_COLUMN_READ);
      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, thd->query_id))
      {
	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->update_row(table->record[1],
					   table->record[0])))
	{
	  updated--;
          if (!ignore || error != HA_ERR_FOUND_DUPP_KEY)
	  {
            /*
              If (ignore && error == HA_ERR_FOUND_DUPP_KEY) we don't have to
              do anything; otherwise...
            */
            if (error != HA_ERR_FOUND_DUPP_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= 1;
          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];
      fill_record(thd, tmp_table->field+1, *values_for_table[offset], 1);
      /* Store pointer to row */
      memcpy((char*) tmp_table->field[0]->ptr,
	     (char*) table->file->ref, table->file->ref_length);
      /* Write row, ignoring duplicated updates to a row */
      if ((error= tmp_table->file->write_row(tmp_table->record[0])))
      {
        if (error != HA_ERR_FOUND_DUPP_KEY &&
            error != HA_ERR_FOUND_DUPP_UNIQUE &&
            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
	}
      }
      else
        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;
  ha_rows org_updated;
  TABLE *table, *tmp_table;
  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)
  {
    byte *ref_pos;
    bool can_compare_record;

    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);

    /*
      Setup copy functions to copy fields from temporary table
    */
    List_iterator_fast<Item> field_it(*fields_for_table[cur_table->shared]);
    Field **field= tmp_table->field+1;		// Skip row pointer
    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->table_flags() &
                          HA_PARTIAL_COLUMN_READ);

    ref_pos= (byte*) tmp_table->field[0]->ptr;
    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;
      }
      if ((local_error= table->file->rnd_pos(table->record[0], ref_pos)))
	goto err;
      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, thd->query_id))
      {
	if ((local_error=table->file->update_row(table->record[1],
						 table->record[0])))
	{
	  if (!ignore || local_error != HA_ERR_FOUND_DUPP_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();
  }
  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();

  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];
  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();
      Query_log_event qinfo(thd, thd->query, thd->query_length,
			    transactional_tables, FALSE);
      if (mysql_bin_log.write(&qinfo) && trans_safe)
	local_error= 1;				// Rollback update
    }
    if (!transactional_tables)
      thd->options|=OPTION_STATUS_NO_TRANS_UPDATE;
  }

  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;
  }


  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,
	    thd->insert_id_used ? thd->last_insert_id : 0L,buff);
  return FALSE;
}