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Fixed bug #29911.

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This bug manifested itself for join queries with GROUP BY and HAVING clauses
whose SELECT lists contained DISTINCT. It occurred when the optimizer could
deduce that the result set would have not more than one row.
The bug could lead to wrong result sets for queries of this type because
HAVING conditions were erroneously ignored in some cases in the function
remove_duplicates.
This commit is contained in:
igor@olga.mysql.com
2007-07-20 22:56:19 -07:00
parent 91dc419715
commit 07e0cd2f4e
3 changed files with 46 additions and 1 deletions
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19
mysql-test/r/having.result
View File

@ -158,3 +158,22 @@ EXPLAIN SELECT 0 AS x, a FROM t1 GROUP BY x,a HAVING x=1 AND a > 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible HAVING
DROP table t1;
CREATE TABLE t1 (a int PRIMARY KEY);
CREATE TABLE t2 (b int PRIMARY KEY, a int);
CREATE TABLE t3 (b int, flag int);
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (1,1), (2,1), (3,1);
INSERT INTO t3(b,flag) VALUES (2, 1);
SELECT t1.a
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
a
SELECT DISTINCT t1.a, MAX(t3.flag)
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
a MAX(t3.flag)
SELECT DISTINCT t1.a
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
a
DROP TABLE t1,t2,t3;

26
mysql-test/t/having.test
View File

@ -151,4 +151,30 @@ EXPLAIN SELECT 0 AS x, a FROM t1 GROUP BY x,a HAVING x=1 AND a > 1;
DROP table t1;
#
# Bug #29911: HAVING clause depending on constant table and evaluated to false
#
CREATE TABLE t1 (a int PRIMARY KEY);
CREATE TABLE t2 (b int PRIMARY KEY, a int);
CREATE TABLE t3 (b int, flag int);
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (1,1), (2,1), (3,1);
INSERT INTO t3(b,flag) VALUES (2, 1);
SELECT t1.a
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
SELECT DISTINCT t1.a, MAX(t3.flag)
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
SELECT DISTINCT t1.a
FROM t1 INNER JOIN t2 ON t1.a=t2.a LEFT JOIN t3 ON t2.b=t3.b
GROUP BY t1.a, t2.b HAVING MAX(t3.flag)=0;
DROP TABLE t1,t2,t3;
# End of 4.1 tests

2
sql/sql_select.cc
View File

@ -8118,7 +8118,7 @@ remove_duplicates(JOIN *join, TABLE *entry,List<Item> &fields, Item *having)
field_count++;
}
if (!field_count && !(join->select_options & OPTION_FOUND_ROWS))
if (!field_count && !(join->select_options & OPTION_FOUND_ROWS) && !having)
{ // only const items with no OPTION_FOUND_ROWS
join->unit->select_limit_cnt= 1; // Only send first row
DBUG_RETURN(0);