/* Copyright (C) 2002-2003 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; either version 2 of the License, or
(at your option) any later version.
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 */
/*
Derived tables
These were introduced by Sinisa <sinisa@mysql.com>
*/
#include "mysql_priv.h"
#include "sql_select.h"
#include "sql_acl.h"
/*
call given derived table processor (preparing or filling tables)
SYNOPSIS
mysql_handle_derived()
lex LEX for this thread
processor procedure of derived table processing
RETURN
0 ok
-1 Error
1 Error and error message given
*/
int
mysql_handle_derived(LEX *lex, int (*processor)(THD*, LEX*, TABLE_LIST*))
{
if (lex->derived_tables)
{
for (SELECT_LEX *sl= lex->all_selects_list;
sl;
sl= sl->next_select_in_list())
{
for (TABLE_LIST *cursor= sl->get_table_list();
cursor;
cursor= cursor->next_local)
{
int res;
if ((res= (*processor)(lex->thd, lex, cursor)))
return res;
}
if (lex->describe)
{
/*
Force join->join_tmp creation, because we will use this JOIN
twice for EXPLAIN and we have to have unchanged join for EXPLAINing
*/
sl->uncacheable|= UNCACHEABLE_EXPLAIN;
sl->master_unit()->uncacheable|= UNCACHEABLE_EXPLAIN;
}
}
}
return 0;
}
/*
Create temporary table structure (but do not fill it)
SYNOPSIS
mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
thd Thread handle
lex LEX for this thread
orig_table_list TABLE_LIST for the upper SELECT
IMPLEMENTATION
Derived table is resolved with temporary table.
After table creation, the above TABLE_LIST is updated with a new table.
This function is called before any command containing derived table
is executed.
Derived tables is stored in thd->derived_tables and freed in
close_thread_tables()
RETURN
0 ok
1 Error
-1 Error and error message given
*/
int mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
{
SELECT_LEX_UNIT *unit= orig_table_list->derived;
int res= 0;
if (unit)
{
SELECT_LEX *first_select= unit->first_select();
TABLE *table= 0;
select_union *derived_result;
bool is_union= first_select->next_select() &&
first_select->next_select()->linkage == UNION_TYPE;
DBUG_ENTER("mysql_derived");
if (!(derived_result= new select_union(0)))
DBUG_RETURN(1); // out of memory
// st_select_lex_unit::prepare correctly work for single select
if ((res= unit->prepare(thd, derived_result, 0)))
goto exit;
derived_result->tmp_table_param.init();
derived_result->tmp_table_param.field_count= unit->types.elements;
/*
Temp table is created so that it hounours if UNION without ALL is to be
processed
*/
if (!(table= create_tmp_table(thd, &derived_result->tmp_table_param,
unit->types, (ORDER*) 0,
is_union && unit->union_distinct, 1,
(first_select->options | thd->options |
TMP_TABLE_ALL_COLUMNS),
HA_POS_ERROR,
orig_table_list->alias)))
{
res= -1;
goto exit;
}
derived_result->set_table(table);
exit:
/*
if it is preparation PS only or commands that need only VIEW structure
then we do not need real data and we can skip execution (and parameters
is not defined, too)
*/
if (res)
{
if (table)
free_tmp_table(thd, table);
delete derived_result;
}
else
{
if (!thd->fill_derived_tables())
delete derived_result;
orig_table_list->derived_result= derived_result;
orig_table_list->table= table;
orig_table_list->real_name= table->real_name;
table->derived_select_number= first_select->select_number;
table->tmp_table= TMP_TABLE;
#ifndef NO_EMBEDDED_ACCESS_CHECKS
table->grant.privilege= SELECT_ACL;
#endif
orig_table_list->db= (char *)"";
// Force read of table stats in the optimizer
table->file->info(HA_STATUS_VARIABLE);
/* Add new temporary table to list of open derived tables */
table->next= thd->derived_tables;
thd->derived_tables= table;
}
}
else if (orig_table_list->ancestor)
orig_table_list->set_ancestor();
return (res);
}
/*
fill derived table
SYNOPSIS
mysql_derived_filling()
thd Thread handle
lex LEX for this thread
unit node that contains all SELECT's for derived tables
orig_table_list TABLE_LIST for the upper SELECT
IMPLEMENTATION
Derived table is resolved with temporary table. It is created based on the
queries defined. After temporary table is filled, if this is not EXPLAIN,
then the entire unit / node is deleted. unit is deleted if UNION is used
for derived table and node is deleted is it is a simple SELECT.
RETURN
0 ok
1 Error
-1 Error and error message given
*/
int mysql_derived_filling(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
{
TABLE *table= orig_table_list->table;
SELECT_LEX_UNIT *unit= orig_table_list->derived;
int res= 0;
/*check that table creation pass without problem and it is derived table */
if (table && unit)
{
SELECT_LEX *first_select= unit->first_select();
select_union *derived_result= orig_table_list->derived_result;
SELECT_LEX *save_current_select= lex->current_select;
bool is_union= first_select->next_select() &&
first_select->next_select()->linkage == UNION_TYPE;
if (is_union)
{
// execute union without clean up
res= unit->exec();
}
else
{
unit->offset_limit_cnt= first_select->offset_limit;
unit->select_limit_cnt= first_select->select_limit+
first_select->offset_limit;
if (unit->select_limit_cnt < first_select->select_limit)
unit->select_limit_cnt= HA_POS_ERROR;
if (unit->select_limit_cnt == HA_POS_ERROR)
first_select->options&= ~OPTION_FOUND_ROWS;
lex->current_select= first_select;
res= mysql_select(thd, &first_select->ref_pointer_array,
(TABLE_LIST*) first_select->table_list.first,
first_select->with_wild,
first_select->item_list, first_select->where,
(first_select->order_list.elements+
first_select->group_list.elements),
(ORDER *) first_select->order_list.first,
(ORDER *) first_select->group_list.first,
first_select->having, (ORDER*) NULL,
(first_select->options | thd->options |
SELECT_NO_UNLOCK),
derived_result, unit, first_select);
}
if (!res)
{
/*
Here we entirely fix both TABLE_LIST and list of SELECT's as
there were no derived tables
*/
if (derived_result->flush())
res= 1;
if (!lex->describe)
unit->cleanup();
}
else
{
free_tmp_table(thd, table);
unit->cleanup();
}
lex->current_select= save_current_select;
if (res)
free_tmp_table(thd, table);
}
return res;
}