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Commit 6dfca7d3 authored by unknown's avatar unknown
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Fix LP BUG#680846 

Analysis:
JOIN::optimize performs constant optimization of GROUP by clauses
by calling remove_const():
    group_list= remove_const(this, (old_group_list= group_list), conds,
                             rollup.state == ROLLUP::STATE_NONE,
			     &simple_group);
If it turns out that a GROUP clause references a field that is
computed by a single-row subquery, then the said optimization
performs premature execution of the subquery referenced by the
group clause.

Solution:
Block the evaluation of subqueries similarly to the approach
for the WHERE and JOIN..ON clauses.
parent 2fa5df5f
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Showing with 151 additions and 5 deletions
mysql-test/r/subselect4.result
View file @ 6dfca7d3
......@@ -526,3 +526,81 @@ id select_type table type possible_keys key key_len ref rows Extra
2 DEPENDENT SUBQUERY t2 index_subquery k k 5 const 2 Using index
DROP TABLE t2;
DROP TABLE t1;
#
# BUG#680846: Crash in clear_tables() with subqueries
#
CREATE TABLE t1 (f3 int) ;
INSERT IGNORE INTO t1 VALUES (0),(0);
CREATE TABLE t2 (f1 int,f3 int,f4 varchar(32)) ;
INSERT IGNORE INTO t2 VALUES (1,0,'f');
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 1 Using temporary; Using filesort
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
COUNT(t2.f3) f9
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 1
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
COUNT(t2.f3) f9
0 2
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 1 Using temporary; Using filesort
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
COUNT(t2.f3) f9
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 1
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
COUNT(t2.f3) f9
0 NULL
drop table t1,t2;
mysql-test/t/subselect4.test
View file @ 6dfca7d3
......@@ -491,3 +491,69 @@ SELECT i FROM t1 WHERE (1) NOT IN (SELECT i FROM t2);
DROP TABLE t2;
DROP TABLE t1;
--echo #
--echo # BUG#680846: Crash in clear_tables() with subqueries
--echo #
CREATE TABLE t1 (f3 int) ;
INSERT IGNORE INTO t1 VALUES (0),(0);
CREATE TABLE t2 (f1 int,f3 int,f4 varchar(32)) ;
INSERT IGNORE INTO t2 VALUES (1,0,'f');
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
SELECT COUNT(t2.f3),
(SELECT COUNT(f3) FROM t1 WHERE t2.f1) AS f9
FROM t2 JOIN t1 ON t1.f3
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
# these queries are like the ones above, but without the ON clause,
# resulting in a different crash (failed assert)
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
GROUP BY f9;
EXPLAIN
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
SELECT COUNT(t2.f3),
(SELECT t2.f1 FROM t1 limit 1) AS f9
FROM t2 JOIN t1
WHERE ('v') IN (SELECT f4 FROM t2)
ORDER BY f9;
drop table t1,t2;
sql/sql_select.cc
View file @ 6dfca7d3
......@@ -8279,13 +8279,15 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
(join->tables > 1 && join->rollup.state == ROLLUP::STATE_INITED &&
join->outer_join))
*simple_order=0; // Must do a temp table to sort
else if (!(order_tables & not_const_tables))
else if (!(order_tables & not_const_tables) &&
!order->item[0]->with_subselect)
{
if (order->item[0]->with_subselect &&
!(join->select_lex->options & SELECT_DESCRIBE))
order->item[0]->val_str(&order->item[0]->str_value);
/*
Skip constant expressions in the ORDER/GROUP clause, except when there
is a subquery in the expression.
*/
DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
continue; // skip const item
continue;
}
else
{
......
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