Fixed LP bug #939009.

The result of materialization of the right part of an IN subquery predicate
is placed into a temporary table. Each row of the materialized table is
distinct. A unique key over all fields of the temporary table is defined and
created. It allows to perform key look-ups into the table.
The table created for a materialized subquery can be accessed by key as
any other table. The function best_access-path search for the best access
to join a table to a given partial join. With some where conditions this
function considers a possibility of a ref_or_null access. If such access
employs the unique key on the temporary table then when estimating
the cost this access the function tries to use the array rec_per_key. Yet,
such array is not built for this unique key. This causes a crash of the server.

Rows returned by the subquery that contain nulls don't have to be placed
into temporary table, as they cannot be match any row produced by the
left part of the subquery predicate. So all fields of the temporary table
can be defined as non-nullable. In this case any ref_or_null access
to the temporary table does not make any sense and it does not make sense
to estimate such an access.

The fix makes sure that the temporary table for a materialized IN subquery
is defined with columns that are all non-nullable. The also ensures that 
any row with nulls returned by the subquery is not placed into the
temporary table.  

1 files changed, 35 insertions, 2 deletions

diff --git a/mysql-test/r/subselect_mat.result b/mysql-test/r/subselect_mat.result
index 4d02e5012e2..baf7e379882 100644
--- a/mysql-test/r/subselect_mat.result
+++ b/mysql-test/r/subselect_mat.result
@@ -1473,7 +1473,7 @@ SET @@optimizer_switch='semijoin=on,materialization=on';
 EXPLAIN SELECT pk FROM t1 WHERE (a) IN (SELECT a FROM t2 WHERE pk > 0);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
-1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	func	1	
 2	MATERIALIZED	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using index condition; Rowid-ordered scan
 SELECT pk FROM t1 WHERE (a) IN (SELECT a FROM t2 WHERE pk > 0);
 pk
@@ -1861,6 +1861,39 @@ WHERE 'condition'='impossible'
 MIN(a)
 NULL
 DROP TABLE t1;
+#
+# BUG#939009: Crash with aggregate function in IN subquery 
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch='materialization=on,semijoin=on';
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (7,1), (4,2), (7,7);
+CREATE TABLE t2 ( c INT );
+INSERT INTO t2 VALUES (4), (7), (6);
+EXPLAIN EXTENDED
+SELECT * FROM t1
+WHERE a IN (SELECT MAX(c) FROM t2) AND b=7 AND (a IS NULL OR a=b);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	<subquery2>	const	distinct_key	distinct_key	4	const	1	100.00	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer (flat, BNL join)
+2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from  <materialize> (select max(`test`.`t2`.`c`) from `test`.`t2`) join `test`.`t1` where ((`test`.`t1`.`a` = `<subquery2>`.`MAX(c)`) and (`test`.`t1`.`b` = 7) and (isnull(`<subquery2>`.`MAX(c)`) or (`<subquery2>`.`MAX(c)` = 7)))
+SELECT * FROM t1
+WHERE a IN (SELECT MAX(c) FROM t2) AND b=7 AND (a IS NULL OR a=b);
+a	b
+EXPLAIN
+SELECT * FROM t1
+WHERE a IN (SELECT MAX(c) FROM t2 WHERE c < 4) AND b=7 AND (a IS NULL OR a=b);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	<subquery2>	const	distinct_key	distinct_key	4	const	1	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where; Using join buffer (flat, BNL join)
+2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	3	Using where
+SELECT * FROM t1
+WHERE a IN (SELECT MAX(c) FROM t2 WHERE c < 4) AND b=7 AND (a IS NULL OR a=b);
+a	b
+SET optimizer_switch=@save_optimizer_switch;
+DROP TABLE t1,t2;
 # This must be at the end:
 set optimizer_switch=@subselect_sj_mat_tmp;
 set join_cache_level=@save_join_cache_level;
@@ -1983,7 +2016,7 @@ SET @@optimizer_switch='default,semijoin=on,materialization=on';
 EXPLAIN SELECT pk FROM t1 WHERE (a) IN (SELECT a FROM t2 WHERE pk > 0);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
-1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	func	1	
 2	MATERIALIZED	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using index condition
 SELECT pk FROM t1 WHERE (a) IN (SELECT a FROM t2 WHERE pk > 0);
 pk