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

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.


mysql-test/r/error_simulation.result:
  test case
mysql-test/t/error_simulation.test:
  test case
sql/item_subselect.cc:
  added new flag subselect_single_select_engine::optimize_error
  which is used for error detection which could happen at optimize
  stage.
sql/item_subselect.h:
  added new flag subselect_single_select_engine::optimize_error
sql/sql_select.cc:
  test case

1 files changed, 13 insertions, 0 deletions

diff --git a/mysql-test/r/error_simulation.result b/mysql-test/r/error_simulation.result
index b6b79cb596b..f1835186787 100644
--- a/mysql-test/r/error_simulation.result
+++ b/mysql-test/r/error_simulation.result
@@ -83,5 +83,18 @@ a	a	b	filler
 SET SESSION debug = DEFAULT;
 DROP TABLE t1, t2;
 #
+# Bug#11747970 34660: CRASH WHEN FEDERATED TABLE LOSES CONNECTION DURING INSERT ... SELECT
+#
+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);
+Warnings:
+Error	1105	Unknown error
+SET SESSION debug = DEFAULT;
+DROP TABLE t1,t2;
+#
 # End of 5.1 tests
 #