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Bug #36011: server crash with explain extended on query

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with dependent subqueries
An IN subquery is executed on EXPLAIN when it's not correlated.
If the subquery required a temporary table for its execution
not all the internal structures were restored from pointing to
the items of the temporary table to point back to the items of
the subquery.
Fixed by restoring the ref array when a temp tables were used in
executing the IN subquery during EXPLAIN EXTENDED.
This commit is contained in:
gkodinov/kgeorge@magare.gmz
2008-05-16 17:05:55 +03:00
parent c86fc51e92
commit df3341a764
3 changed files with 31 additions and 4 deletions
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15
mysql-test/r/subselect.result
View File

@ -4381,4 +4381,19 @@ t1.a= (select b from t2 limit 1) and not
t1.a= (select a from t2 limit 1) ;
a
drop table t1, t2;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 GROUP BY a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using temporary; Using filesort
Warnings:
Note 1003 select 1 AS `1` from `test`.`t1` where <in_optimizer>(1,<exists>(select 1 AS `1` from `test`.`t1` group by `test`.`t1`.`a` having (<cache>(1) = <ref_null_helper>(1))))
EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 WHERE a > 3 GROUP BY a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where; Using temporary; Using filesort
Warnings:
Note 1003 select 1 AS `1` from `test`.`t1` where <in_optimizer>(1,<exists>(select 1 AS `1` from `test`.`t1` where (`test`.`t1`.`a` > 3) group by `test`.`t1`.`a` having (<cache>(1) = <ref_null_helper>(1))))
DROP TABLE t1;
End of 5.0 tests.

11
mysql-test/t/subselect.test
View File

@ -3271,5 +3271,16 @@ select t1.a from t1 where
drop table t1, t2;
#
# Bug #36011: Server crash with explain extended on query with dependent
# subqueries
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 GROUP BY a);
EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 WHERE a > 3 GROUP BY a);
DROP TABLE t1;
--echo End of 5.0 tests.

7
sql/sql_select.cc
View File

@ -2104,11 +2104,12 @@ JOIN::exec()
/*
With EXPLAIN EXTENDED we have to restore original ref_array
for a derived table which is always materialized.
We also need to do this when we have temp table(s).
Otherwise we would not be able to print the query correctly.
*/
if (items0 &&
(thd->lex->describe & DESCRIBE_EXTENDED) &&
select_lex->linkage == DERIVED_TABLE_TYPE)
if (items0 && (thd->lex->describe & DESCRIBE_EXTENDED) &&
(select_lex->linkage == DERIVED_TABLE_TYPE ||
exec_tmp_table1 || exec_tmp_table2))
set_items_ref_array(items0);
DBUG_VOID_RETURN;