MDEV-17024 Crash on large query

This problem manifested itself when a join query used two or more
materialized CTE such that each of them employed the same recursive CTE.
The bug caused a crash. The crash happened because the cleanup()
function was performed premature for recursive CTE. This clean up was
induced by the cleanup of the first CTE referenced the recusrsive CTE.
This cleanup destroyed the structures that would allow to read from the
temporary table containing the rows of the recursive CTE and an attempt to read
these rows for the second CTE referencing the recursive CTE triggered a
crash.
The clean up for a recursive CTE R should be performed after the cleanup
of the last materialized CTE that uses R.

1 files changed, 93 insertions, 0 deletions

diff --git a/mysql-test/r/cte_recursive.result b/mysql-test/r/cte_recursive.result
index c892c76b33e..55733bede38 100644
--- a/mysql-test/r/cte_recursive.result
+++ b/mysql-test/r/cte_recursive.result
@@ -3300,3 +3300,96 @@ SELECT func();
 func()
 1
 DROP FUNCTION func;
+#
+# MDEV-17024: two materialized CTEs using the same recursive CTE
+#
+create table t1 (id int);
+insert into t1 values (1), (2), (3);
+with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1, cte2;
+c1	c2
+2	1
+explain extended with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1, cte2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	<derived4>	ALL	NULL	NULL	NULL	NULL	6	100.00	
+1	PRIMARY	<derived5>	ALL	NULL	NULL	NULL	NULL	6	100.00	Using join buffer (flat, BNL join)
+4	DERIVED	<derived2>	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+4	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer (flat, BNL join)
+5	DERIVED	<derived2>	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+5	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer (flat, BNL join)
+2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	RECURSIVE UNION	<derived2>	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+Warnings:
+Note	1003	with recursive rcte as (select 1 AS `a` union select cast(`rcte`.`a` + 1 as unsigned) AS `cast(a+1 as unsigned)` from `rcte` where `rcte`.`a` < 10), cte1 as (select count(0) AS `c1` from `rcte` join `test`.`t1` where `rcte`.`a` between 3 and 5 and `test`.`t1`.`id` = `rcte`.`a` - 3), cte2 as (select count(0) AS `c2` from `rcte` join `test`.`t1` where `rcte`.`a` between 7 and 8 and `test`.`t1`.`id` = `rcte`.`a` - 7)select `cte1`.`c1` AS `c1`,`cte2`.`c2` AS `c2` from `cte1` join `cte2`
+prepare stmt from "with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1, cte2";
+execute stmt;
+c1	c2
+2	1
+execute stmt;
+c1	c2
+2	1
+create table t2 (c1 int, c2 int);
+create procedure p() insert into t2 with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1, cte2;
+call p();
+select * from t2;
+c1	c2
+2	1
+with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1;
+c1
+2
+with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from t1),
+cte2 as
+(select count(*) as c2 from t2)
+select * from cte1,cte2;
+c1	c2
+3	1
+with recursive
+rcte(a) as
+(select 1 union select cast(a+1 as unsigned) from rcte where a < 10),
+cte1 as
+(select count(*) as c1 from rcte,t1 where a between 3 and 5 and id=a-3),
+cte2 as
+(select count(*) as c2 from rcte,t1 where a between 7 and 8 and id=a-7)
+select * from cte1, cte2 where cte1.c1 = 3;
+c1	c2
+drop procedure p;
+drop table t1,t2;