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MDEV-21883 Server crashes when joining a subselect with 32 tables and GROUP BY

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This bug could cause a crash for any query that used a derived table/view/CTE
whose specification was a SELECT with a GROUP BY clause and a FROM list
containing 32 or more table references.
The problem appeared only in the cases when the splitting optimization
could be applied to such derived table/view/CTE.
This commit is contained in:
Igor Babaev 2020-03-23 19:20:48 -07:00
parent fd5c36bed5
commit caf110fa52
3 changed files with 137 additions and 1 deletions
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85
mysql-test/main/derived_cond_pushdown.result
View File

@ -16918,4 +16918,89 @@ Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`id` AS `id`,`test`.`t1`.`a` AS `a` from `test`.`t1` semi join ((/* select#3 */ select `test`.`t1`.`id` AS `id`,`test`.`t1`.`a` AS `a` from `test`.`t1` left join `test`.`t2` on(`test`.`t2`.`ro_id` = `test`.`t1`.`id` and `test`.`t2`.`flag` = 1) where `test`.`t1`.`id` = `test`.`t1`.`id` group by `test`.`t1`.`id`) `dt`) where `dt`.`id` = `test`.`t1`.`id`
drop view v1;
drop table t1,t2;
#
# MDEV-21883: potentially splittable materialized derived
# that uses a join of 32 tables
#
CREATE TABLE t (id INT NOT NULL PRIMARY KEY);
INSERT INTO t values (1),(2),(3);
set statement optimizer_switch='split_materialized=off' for SELECT t.id FROM t
LEFT JOIN (
SELECT t0.id FROM t AS t0
LEFT JOIN t AS t1 ON 0=1
LEFT JOIN t AS t2 ON 0=1
LEFT JOIN t AS t3 ON 0=1
LEFT JOIN t AS t4 ON 0=1
LEFT JOIN t AS t5 ON 0=1
LEFT JOIN t AS t6 ON 0=1
LEFT JOIN t AS t7 ON 0=1
LEFT JOIN t AS t8 ON 0=1
LEFT JOIN t AS t9 ON 0=1
LEFT JOIN t AS t10 ON 0=1
LEFT JOIN t AS t11 ON 0=1
LEFT JOIN t AS t12 ON 0=1
LEFT JOIN t AS t13 ON 0=1
LEFT JOIN t AS t14 ON 0=1
LEFT JOIN t AS t15 ON 0=1
LEFT JOIN t AS t16 ON 0=1
LEFT JOIN t AS t17 ON 0=1
LEFT JOIN t AS t18 ON 0=1
LEFT JOIN t AS t19 ON 0=1
LEFT JOIN t AS t20 ON 0=1
LEFT JOIN t AS t21 ON 0=1
LEFT JOIN t AS t22 ON 0=1
LEFT JOIN t AS t23 ON 0=1
LEFT JOIN t AS t24 ON 0=1
LEFT JOIN t AS t25 ON 0=1
LEFT JOIN t AS t26 ON 0=1
LEFT JOIN t AS t27 ON 0=1
LEFT JOIN t AS t28 ON 0=1
LEFT JOIN t AS t29 ON 0=1
LEFT JOIN t AS t30 ON 0=1
LEFT JOIN t AS t31 ON 0=1
GROUP BY t0.id) AS dt ON dt.id = t.id;
id
1
2
3
set statement optimizer_switch='split_materialized=on' for SELECT t.id FROM t
LEFT JOIN (
SELECT t0.id FROM t AS t0
LEFT JOIN t AS t1 ON 0=1
LEFT JOIN t AS t2 ON 0=1
LEFT JOIN t AS t3 ON 0=1
LEFT JOIN t AS t4 ON 0=1
LEFT JOIN t AS t5 ON 0=1
LEFT JOIN t AS t6 ON 0=1
LEFT JOIN t AS t7 ON 0=1
LEFT JOIN t AS t8 ON 0=1
LEFT JOIN t AS t9 ON 0=1
LEFT JOIN t AS t10 ON 0=1
LEFT JOIN t AS t11 ON 0=1
LEFT JOIN t AS t12 ON 0=1
LEFT JOIN t AS t13 ON 0=1
LEFT JOIN t AS t14 ON 0=1
LEFT JOIN t AS t15 ON 0=1
LEFT JOIN t AS t16 ON 0=1
LEFT JOIN t AS t17 ON 0=1
LEFT JOIN t AS t18 ON 0=1
LEFT JOIN t AS t19 ON 0=1
LEFT JOIN t AS t20 ON 0=1
LEFT JOIN t AS t21 ON 0=1
LEFT JOIN t AS t22 ON 0=1
LEFT JOIN t AS t23 ON 0=1
LEFT JOIN t AS t24 ON 0=1
LEFT JOIN t AS t25 ON 0=1
LEFT JOIN t AS t26 ON 0=1
LEFT JOIN t AS t27 ON 0=1
LEFT JOIN t AS t28 ON 0=1
LEFT JOIN t AS t29 ON 0=1
LEFT JOIN t AS t30 ON 0=1
LEFT JOIN t AS t31 ON 0=1
GROUP BY t0.id) AS dt ON dt.id = t.id;
id
1
2
3
DROP TABLE t;
# End of 10.3 tests

51
mysql-test/main/derived_cond_pushdown.test
View File

@ -3371,4 +3371,55 @@ eval explain extended $q2;
drop view v1;
drop table t1,t2;
--echo #
--echo # MDEV-21883: potentially splittable materialized derived
--echo # that uses a join of 32 tables
--echo #
CREATE TABLE t (id INT NOT NULL PRIMARY KEY);
INSERT INTO t values (1),(2),(3);
let $q=
SELECT t.id FROM t
LEFT JOIN (
SELECT t0.id FROM t AS t0
LEFT JOIN t AS t1 ON 0=1
LEFT JOIN t AS t2 ON 0=1
LEFT JOIN t AS t3 ON 0=1
LEFT JOIN t AS t4 ON 0=1
LEFT JOIN t AS t5 ON 0=1
LEFT JOIN t AS t6 ON 0=1
LEFT JOIN t AS t7 ON 0=1
LEFT JOIN t AS t8 ON 0=1
LEFT JOIN t AS t9 ON 0=1
LEFT JOIN t AS t10 ON 0=1
LEFT JOIN t AS t11 ON 0=1
LEFT JOIN t AS t12 ON 0=1
LEFT JOIN t AS t13 ON 0=1
LEFT JOIN t AS t14 ON 0=1
LEFT JOIN t AS t15 ON 0=1
LEFT JOIN t AS t16 ON 0=1
LEFT JOIN t AS t17 ON 0=1
LEFT JOIN t AS t18 ON 0=1
LEFT JOIN t AS t19 ON 0=1
LEFT JOIN t AS t20 ON 0=1
LEFT JOIN t AS t21 ON 0=1
LEFT JOIN t AS t22 ON 0=1
LEFT JOIN t AS t23 ON 0=1
LEFT JOIN t AS t24 ON 0=1
LEFT JOIN t AS t25 ON 0=1
LEFT JOIN t AS t26 ON 0=1
LEFT JOIN t AS t27 ON 0=1
LEFT JOIN t AS t28 ON 0=1
LEFT JOIN t AS t29 ON 0=1
LEFT JOIN t AS t30 ON 0=1
LEFT JOIN t AS t31 ON 0=1
GROUP BY t0.id) AS dt ON dt.id = t.id;
eval set statement optimizer_switch='split_materialized=off' for $q;
eval set statement optimizer_switch='split_materialized=on' for $q;
DROP TABLE t;
--echo # End of 10.3 tests

2
sql/opt_split.cc
View File

@ -968,7 +968,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count,
The plan for the chosen key has not been found in the cache.
Build a new plan and save info on it in the cache
*/
table_map all_table_map= (1 << join->table_count) - 1;
table_map all_table_map= (((table_map) 1) << join->table_count) - 1;
reset_validity_vars_for_keyuses(best_key_keyuse_ext_start, best_table,
best_key, remaining_tables, true);
choose_plan(join, all_table_map & ~join->const_table_map);