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Bug#11747970 34660: CRASH WHEN FEDERATED TABLE LOSES CONNECTION DURING INSERT ... SELECT

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Problematic query:
insert ignore into `t1_federated` (`c1`) select `c1` from  `t1_local` a
where not exists (select 1 from `t1_federated` b where a.c1 = b.c1);
When this query is killed in another connection it could lead to crash.
The problem is follwing:
An attempt to obtain table statistics for subselect table in killed query
fails with an error. So JOIN::optimize() for subquery is failed but
it does not prevent further subquery evaluation.
At the first subquery execution JOIN::optimize() is called
(see subselect_single_select_engine::exec()) and fails with
an error. 'executed' flag is set to TRUE and it prevents
further subquery evaluation. At the second call
JOIN::optimize() does not happen as 'JOIN::optimized' is TRUE
and in case of uncacheable subquery the 'executed' flag is set
to FALSE before subquery evaluation. So we loose 'optimize stage'
error indication (see subselect_single_select_engine::exec()).
In other words 'executed' flag is used for two purposes, for
error indication at JOIN::optimize() stage and for an
indication of subquery execution. And it seems it's wrong
as the flag could be reset.
This commit is contained in:
Sergey Glukhov
2011-10-05 13:28:20 +04:00
parent 836c3a2378
commit fcd99c156b
5 changed files with 48 additions and 3 deletions
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14
mysql-test/t/error_simulation.test
View File

@ -89,6 +89,20 @@ SET SESSION debug = DEFAULT;
DROP TABLE t1, t2;
--echo #
--echo # Bug#11747970 34660: CRASH WHEN FEDERATED TABLE LOSES CONNECTION DURING INSERT ... SELECT
--echo #
CREATE TABLE t1(f1 INT, KEY(f1));
CREATE TABLE t2(f1 INT);
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (1),(2);
SET SESSION debug='d,bug11747970_simulate_error';
INSERT IGNORE INTO t2 SELECT f1 FROM t1 a WHERE NOT EXISTS (SELECT 1 FROM t2 b WHERE a.f1 = b.f1);
SET SESSION debug = DEFAULT;
DROP TABLE t1,t2;
--echo #
--echo # End of 5.1 tests
--echo #