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MDEV-16104 Server crash in JOIN::fix_all_splittings_in_plan

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upon select with view and subqueries

This bug occurred when a splittable materialized derived/view
were used inside another splittable materialized derived/view.
The bug happened because the function JOIN::fix_all_splittings_in_plan()
was called at the very beginning of the optimization phase 2 at
the moment when the plan structure of the embedding derived/view
were not valid. The proper position for this call is the very
end of the optimization phase 1.
This commit is contained in:
Igor Babaev
2018-05-08 23:32:11 -07:00
parent 2deb17fd54
commit fc0f5adb7f
3 changed files with 68 additions and 3 deletions
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33
mysql-test/main/derived_cond_pushdown.result
View File

@ -15164,3 +15164,36 @@ id select_type table type possible_keys key key_len ref rows Extra
3 DERIVED t1 ALL NULL NULL NULL NULL 5 Using temporary
2 DERIVED t1 ALL NULL NULL NULL NULL 5 Using temporary; Using filesort
drop table t1;
#
# MDEV-16104: embedded splittable materialized derived/views
#
CREATE TABLE t1 (f int PRIMARY KEY) ENGINE=MyISAM;
INSERT INTO t1
VALUES (3), (7), (1), (4), (8), (5), (9);
CREATE ALGORITHM=MERGE VIEW v1 AS
SELECT a2.*
FROM
( SELECT f, COUNT(*) as c FROM t1 GROUP BY f ) AS a1
JOIN
t1 AS a2
USING (f);
EXPLAIN EXTENDED
SELECT * FROM ( SELECT STRAIGHT_JOIN f, COUNT(*) as c FROM v1 GROUP BY f ) AS s;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 7 100.00
2 DERIVED <derived4> ALL NULL NULL NULL NULL 7 100.00 Using temporary; Using filesort
2 DERIVED a2 eq_ref PRIMARY PRIMARY 4 a1.f 1 100.00 Using index
4 DERIVED t1 index PRIMARY PRIMARY 4 NULL 7 100.00 Using index; Using temporary; Using filesort
Warnings:
Note 1003 /* select#1 */ select `s`.`f` AS `f`,`s`.`c` AS `c` from (/* select#2 */ select straight_join `a2`.`f` AS `f`,count(0) AS `c` from ((/* select#4 */ select `test`.`t1`.`f` AS `f`,count(0) AS `c` from `test`.`t1` group by `test`.`t1`.`f`)) `a1` join `test`.`t1` `a2` where `a2`.`f` = `a1`.`f` group by `a2`.`f`) `s`
SELECT * FROM ( SELECT STRAIGHT_JOIN f, COUNT(*) as c FROM v1 GROUP BY f ) AS s;
f c
1 1
3 1
4 1
5 1
7 1
8 1
9 1
DROP VIEW v1;
DROP TABLE t1;

23
mysql-test/main/derived_cond_pushdown.test
View File

@ -2690,3 +2690,26 @@ eval $q;
eval explain $q;
drop table t1;
--echo #
--echo # MDEV-16104: embedded splittable materialized derived/views
--echo #
CREATE TABLE t1 (f int PRIMARY KEY) ENGINE=MyISAM;
INSERT INTO t1
VALUES (3), (7), (1), (4), (8), (5), (9);
CREATE ALGORITHM=MERGE VIEW v1 AS
SELECT a2.*
FROM
( SELECT f, COUNT(*) as c FROM t1 GROUP BY f ) AS a1
JOIN
t1 AS a2
USING (f);
EXPLAIN EXTENDED
SELECT * FROM ( SELECT STRAIGHT_JOIN f, COUNT(*) as c FROM v1 GROUP BY f ) AS s;
SELECT * FROM ( SELECT STRAIGHT_JOIN f, COUNT(*) as c FROM v1 GROUP BY f ) AS s;
DROP VIEW v1;
DROP TABLE t1;

15
sql/sql_select.cc
View File

@ -1853,6 +1853,18 @@ JOIN::optimize_inner()
DBUG_RETURN(1);
}
/*
If a splittable materialized derived/view dt_i is embedded into
into another splittable materialized derived/view dt_o then
splitting plans for dt_i and dt_o are evaluated independently.
First the optimizer looks for the best splitting plan sp_i for dt_i.
It happens when non-splitting plans for dt_o are evaluated.
The cost of sp_i is considered as the cost of materialization of dt_i
when evaluating any splitting plan for dt_o.
*/
if (fix_all_splittings_in_plan())
DBUG_RETURN(1);
setup_subq_exit:
with_two_phase_optimization= check_two_phase_optimization(thd);
if (with_two_phase_optimization)
@ -9374,9 +9386,6 @@ bool JOIN::get_best_combination()
full_join=0;
hash_join= FALSE;
if (fix_all_splittings_in_plan())
DBUG_RETURN(TRUE);
fix_semijoin_strategies_for_picked_join_order(this);
JOIN_TAB_RANGE *root_range;