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Fix UNION

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New faster list iterators
Change list code to be simpler and faster
Optimize count(distinct)
New error messages for UNION
Make create_tmp_table more general to be usable by UNION
This commit is contained in:
monty@tik.mysql.fi
2001-08-02 06:29:50 +03:00
parent 423f2851c5
commit b13d453d50
57 changed files with 798 additions and 472 deletions
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217
sql/sql_union.cc Normal file
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@ -0,0 +1,217 @@
/* Copyright (C) 2000 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 */
/*
UNION of select's
UNION's were introduced by Monty and Sinisa <sinisa@mysql.com>
*/
#include "mysql_priv.h"
#include "sql_select.h"
int mysql_union(THD *thd, LEX *lex)
{
SELECT_LEX *sl, *last_sl;
ORDER *order;
List<Item> item_list;
/* TABLE_LIST *s=(TABLE_LIST*) lex->select_lex.table_list.first; */
TABLE *table;
TABLE_LIST *first_table, result_table_list;
TMP_TABLE_PARAM tmp_table_param;
select_result *result;
select_union *union_result;
int res;
uint elements;
DBUG_ENTER("mysql_union");
/* Find last select part as it's here ORDER BY and GROUP BY is stored */
elements= lex->select_lex.item_list.elements;
for (last_sl= &lex->select_lex;
last_sl->next;
last_sl=last_sl->next)
{
if (elements != last_sl->next->item_list.elements)
{
my_error(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,MYF(0));
return -1;
}
}
order = (ORDER *) last_sl->order_list.first;
{
Item *item;
List_iterator<Item> it(lex->select_lex.item_list);
/* Create a list of items that will be in the result set */
first_table= (TABLE_LIST*) lex->select_lex.table_list.first;
while ((item= it++))
if (item_list.push_back(item))
DBUG_RETURN(-1);
if (setup_fields(thd,first_table,item_list,0,0,1))
DBUG_RETURN(-1);
}
bzero((char*) &tmp_table_param,sizeof(tmp_table_param));
tmp_table_param.field_count=elements;
if (!(table=create_tmp_table(thd, &tmp_table_param, item_list,
(ORDER*) 0, !lex->union_option,
1, 0,
(lex->select_lex.options | thd->options |
TMP_TABLE_ALL_COLUMNS))))
DBUG_RETURN(-1);
table->file->extra(HA_EXTRA_WRITE_CACHE);
table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
bzero((char*) &result_table_list,sizeof(result_table_list));
result_table_list.db= (char*) "";
result_table_list.real_name=result_table_list.name=(char*) "union";
result_table_list.table=table;
if (!(union_result=new select_union(table)))
{
res= -1;
goto exit;
}
for (sl= &lex->select_lex; sl; sl=sl->next)
{
thd->offset_limit=sl->offset_limit;
thd->select_limit=sl->select_limit+sl->offset_limit;
if (thd->select_limit < sl->select_limit)
thd->select_limit= HA_POS_ERROR; // no limit
if (thd->select_limit == HA_POS_ERROR)
sl->options&= ~OPTION_FOUND_ROWS;
res=mysql_select(thd,(TABLE_LIST*) sl->table_list.first,
sl->item_list,
sl->where,
sl->ftfunc_list,
(ORDER*) 0,
(ORDER*) sl->group_list.first,
sl->having,
(ORDER*) NULL,
sl->options | thd->options | SELECT_NO_UNLOCK,
union_result);
if (res)
goto exit;
}
if (union_result->flush())
{
res= 1; // Error is already sent
goto exit;
}
delete union_result;
/*
Sinisa, we must also be able to handle
CREATE TABLE ... and INSERT ... SELECT with unions
To do this, it's probably best that we add a new handle_select() function
which takes 'select_result' as parameter and let this internally handle
SELECT with and without unions.
*/
if (lex->exchange)
{
if (lex->exchange->dumpfile)
result=new select_dump(lex->exchange);
else
result=new select_export(lex->exchange);
}
else
result=new select_send();
res =-1;
if (result)
{
/* Create a list of fields in the temporary table */
List_iterator<Item> it(item_list);
Field **field;
List<Item_func_match> ftfunc_list;
ftfunc_list.empty();
for (field=table->field ; *field ; field++)
{
(void) it++;
(void) it.replace(new Item_field(*field));
}
if (!thd->fatal_error) // Check if EOM
res=mysql_select(thd,&result_table_list,
item_list, NULL, ftfunc_list, order,
(ORDER*) NULL, NULL, (ORDER*) NULL,
thd->options, result);
if (res)
result->abort();
delete result;
}
exit:
free_tmp_table(thd,table);
DBUG_RETURN(res);
}
/***************************************************************************
** store records in temporary table for UNION
***************************************************************************/
select_union::select_union(TABLE *table_par)
:table(table_par)
{
bzero((char*) &info,sizeof(info));
/*
We can always use DUP_IGNORE because the temporary table will only
contain a unique key if we are using not using UNION ALL
*/
info.handle_duplicates=DUP_IGNORE;
}
select_union::~select_union()
{
}
int select_union::prepare(List<Item> &list)
{
return 0;
}
bool select_union::send_data(List<Item> &values)
{
if (thd->offset_limit)
{ // using limit offset,count
thd->offset_limit--;
return 0;
}
fill_record(table->field,values);
return write_record(table,&info) ? 1 : 0;
}
bool select_union::send_eof()
{
return 0;
}
bool select_union::flush()
{
int error,error2;
error=table->file->extra(HA_EXTRA_NO_CACHE);
if (error)
{
table->file->print_error(error,MYF(0));
::send_error(&thd->net);
return 1;
}
return 0;
}