Subquery materialization is not used in CREATE TABLE SELECT

Bug #938131 reported by Igor Babaev on 2012-02-21
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
MariaDB
Fix Released
High
Sergey Petrunia

Bug Description

Using mariadb-5.3 create and populate table t1,t2 with the following commands:

CREATE TABLE t1(a int);
INSERT INTO t1 values(1),(2);
CREATE TABLE t2(a int);
INSERT INTO t2 values(1),(2);

Then check that the following query uses subquery materialization:
SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);

MariaDB [test]> EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);
+----+--------------+-------------+--------+---------------+--------------+---------+-----------+------+-----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------+-------------+--------+---------------+--------------+---------+-----------+------+-----------------+
| 1 | PRIMARY | t1 | ALL | NULL | NULL | NULL | NULL | 2 | Using where |
| 1 | PRIMARY | <subquery2> | eq_ref | distinct_key | distinct_key | 5 | test.t1.a | 1 | |
| 2 | MATERIALIZED | t2 | ALL | NULL | NULL | NULL | NULL | 2 | Using temporary |
+----+--------------+-------------+--------+---------------+--------------+---------+-----------+------+-----------------+

In debugger check that materialization is not used for :

CREATE TABLE t3 SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);

Changed in maria:
importance: Undecided → High
status: New → Confirmed
assignee: nobody → Sergey Petrunia (sergefp)
Changed in maria:
milestone: none → 5.3
Changed in maria:
status: Confirmed → Fix Committed
Elena Stepanova (elenst) wrote :

Fix released with 5.3.5-ga.

Changed in maria:
status: Fix Committed → Fix Released
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