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Fix for a bug with EXPLAIN and (....) UNION (....) order by

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Sinisa@sinisa.nasamreza.org 2002-04-02 20:08:55 +03:00
parent 2f7a8c0f04
commit b98a84a19f
3 changed files with 11 additions and 3 deletions
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5
mysql-test/r/union.result
View File

@ -84,6 +84,11 @@ a b
3 c
2 b
1 a
explain (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 4
t2 ALL NULL NULL NULL NULL 4 Using filesort
t1 ALL NULL NULL NULL NULL 4
explain select a,b from t1 union all select a,b from t2;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 4

1
mysql-test/t/union.test
View File

@ -20,6 +20,7 @@ select 't1',b,count(*) from t1 group by b UNION select 't2',b,count(*) from t2 g
(select a,b from t1 limit 2) union all (select a,b from t2 order by a) limit 4;
(select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1);
(select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc;
explain (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc;
# Test some error conditions with UNION
explain select a,b from t1 union all select a,b from t2;

8
sql/sql_union.cc
View File

@ -34,6 +34,7 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
int describe=(lex->select_lex.options & SELECT_DESCRIBE) ? 1 : 0;
int res;
TABLE_LIST result_table_list;
TABLE_LIST *first_table=(TABLE_LIST *)lex->select_lex.table_list.first;
TMP_TABLE_PARAM tmp_table_param;
select_union *union_result;
DBUG_ENTER("mysql_union");
@ -58,8 +59,9 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
the ORDER BY and LIMIT parameter for the whole UNION
*/
lex_sl= sl;
last_sl->next=0; // Remove this extra element
order= (ORDER *) lex_sl->order_list.first;
if (!order || !describe)
last_sl->next=0; // Remove this extra element
}
else if (!last_sl->braces)
{
@ -136,7 +138,7 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
if (thd->select_limit == HA_POS_ERROR)
sl->options&= ~OPTION_FOUND_ROWS;
res=mysql_select(thd, (TABLE_LIST*) sl->table_list.first,
res=mysql_select(thd, (describe && sl->linkage==NOT_A_SELECT) ? first_table : (TABLE_LIST*) sl->table_list.first,
sl->item_list,
sl->where,
(sl->braces) ? (ORDER *)sl->order_list.first : (ORDER *) 0,
@ -193,7 +195,7 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
if (describe)
thd->select_limit= HA_POS_ERROR; // no limit
res=mysql_select(thd,&result_table_list,
item_list, NULL, /*ftfunc_list,*/ order,
item_list, NULL, (describe) ? 0 : order,
(ORDER*) NULL, NULL, (ORDER*) NULL,
thd->options, result);
}