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Bug #52711: Segfault when doing EXPLAIN SELECT with

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union...order by (select... where...)

The problem is mysql is trying to materialize and 
cache the scalar sub-queries at JOIN::optimize
even for EXPLAIN where the number of columns is 
totally different from what's expected.
Fixed by not executing the scalar subqueries 
for EXPLAIN.
This commit is contained in:
Georgi Kodinov 2010-04-15 17:04:24 +03:00
parent 5b54e86ec1
commit a8ae3cd6e9
3 changed files with 44 additions and 1 deletions
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17
mysql-test/r/subselect.result
View file

@ -4717,3 +4717,20 @@ t1_id total_amount
DROP TABLE t3;
DROP TABLE t2;
DROP TABLE t1;
#
# Bug #52711: Segfault when doing EXPLAIN SELECT with
# union...order by (select... where...)
#
CREATE TABLE t1 (a VARCHAR(10), FULLTEXT KEY a (a));
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1),(2);
# Should not crash
EXPLAIN
SELECT * FROM t2 UNION SELECT * FROM t2
ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
# Should not crash
SELECT * FROM t2 UNION SELECT * FROM t2
ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
DROP TABLE t1,t2;
End of 5.1 tests

25
mysql-test/t/subselect.test
View file

@ -3701,3 +3701,28 @@ GROUP BY
DROP TABLE t3;
DROP TABLE t2;
DROP TABLE t1;
--echo #
--echo # Bug #52711: Segfault when doing EXPLAIN SELECT with
--echo # union...order by (select... where...)
--echo #
CREATE TABLE t1 (a VARCHAR(10), FULLTEXT KEY a (a));
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1),(2);
--echo # Should not crash
--disable_result_log
EXPLAIN
SELECT * FROM t2 UNION SELECT * FROM t2
ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
--echo # Should not crash
SELECT * FROM t2 UNION SELECT * FROM t2
ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
DROP TABLE t1,t2;
--enable_result_log
--echo End of 5.1 tests

3
sql/sql_select.cc
View file

@ -7210,7 +7210,8 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
*simple_order=0; // Must do a temp table to sort
else if (!(order_tables & not_const_tables))
{
if (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);
DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
continue; // skip const item