Commit b98a84a1 authored by Sinisa@sinisa.nasamreza.org's avatar Sinisa@sinisa.nasamreza.org
Browse files

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

parent 2f7a8c0f

mysql-test/r/union.result

+5 −0
Original line number Diff line number Diff line
@@ -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

mysql-test/t/union.test

+1 −0
Original line number Diff line number Diff line
@@ -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;

sql/sql_union.cc

+5 −3
Original line number Diff line number Diff line
@@ -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);

    }