revision-id: 08ef3c3ee2832db89f4d088ff407b794f31cfc50 (mariadb-10.3.18-153-g08ef3c3) parent(s): bc43bf3e430c20bc2178e584215bd443054709d6 author: Igor Babaev committer: Igor Babaev timestamp: 2020-02-07 19:42:11 -0800 message: MDEV-21614 Wrong query results with optimizer_switch="split_materialized=on" Do not materialize a semi-join nest if it contains a materialized derived table /view that potentially can be subject to the split optimization. Splitting of materialization of such nest would help, but currently there is no code to support this technique. --- mysql-test/main/derived_cond_pushdown.result | 89 ++++++++++++++++++++++++++++ mysql-test/main/derived_cond_pushdown.test | 43 ++++++++++++++ sql/opt_split.cc | 11 +++- 3 files changed, 142 insertions(+), 1 deletion(-) diff --git a/mysql-test/main/derived_cond_pushdown.result b/mysql-test/main/derived_cond_pushdown.result index 19c4ee8..1ae78ae 100644 --- a/mysql-test/main/derived_cond_pushdown.result +++ b/mysql-test/main/derived_cond_pushdown.result @@ -16829,4 +16829,93 @@ id username id userid logindate 2 user2 3 2 2017-06-19 12:17:02 set join_cache_level=default; DROP TABLE t1,t2; +# +# MDEV-21614: potentially splittable materialized derived/view +# within materialized semi-join +# +create table t1 ( +id int not null auto_increment primary key, +a int not null +) engine=myisam; +create table t2 ( +id int not null auto_increment primary key, +ro_id int not null, +flag int not null, key (ro_id) +) engine=myisam; +insert into t1(a) select seq+100 from seq_1_to_20; +insert into t2(ro_id,flag) select seq, 1 from seq_1_to_20; +insert into t2(ro_id,flag) select seq, 0 from seq_1_to_20; +create view v1 as +select t1.* from t1 left join t2 on (t1.id = t2.ro_id AND t2.flag = 1) +group by t1.id; +select id, a from t1 where id in (select id from v1); +id a +1 101 +2 102 +3 103 +4 104 +5 105 +6 106 +7 107 +8 108 +9 109 +10 110 +11 111 +12 112 +13 113 +14 114 +15 115 +16 116 +17 117 +18 118 +19 119 +20 120 +explain extended select id, a from t1 where id in (select id from v1); +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 20 100.00 +1 PRIMARY <derived3> ref key0 key0 4 test.t1.id 2 100.00 FirstMatch(t1) +3 LATERAL DERIVED t1 eq_ref PRIMARY PRIMARY 4 test.t1.id 1 100.00 +3 LATERAL DERIVED t2 ref ro_id ro_id 4 test.t1.id 1 100.00 Using where +Warnings: +Note 1003 /* select#1 */ select `test`.`t1`.`id` AS `id`,`test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`v1`) where `v1`.`id` = `test`.`t1`.`id` +select id, a from t1 +where id in (select id +from (select t1.* from t1 left join t2 +on (t1.id = t2.ro_id AND t2.flag = 1) +group by t1.id) dt); +id a +1 101 +2 102 +3 103 +4 104 +5 105 +6 106 +7 107 +8 108 +9 109 +10 110 +11 111 +12 112 +13 113 +14 114 +15 115 +16 116 +17 117 +18 118 +19 119 +20 120 +explain extended select id, a from t1 +where id in (select id +from (select t1.* from t1 left join t2 +on (t1.id = t2.ro_id AND t2.flag = 1) +group by t1.id) dt); +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 20 100.00 +1 PRIMARY <derived3> ref key0 key0 4 test.t1.id 2 100.00 FirstMatch(t1) +3 LATERAL DERIVED t1 eq_ref PRIMARY PRIMARY 4 test.t1.id 1 100.00 +3 LATERAL DERIVED t2 ref ro_id ro_id 4 test.t1.id 1 100.00 Using where +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; # End of 10.3 tests diff --git a/mysql-test/main/derived_cond_pushdown.test b/mysql-test/main/derived_cond_pushdown.test index e3a7306..525122e 100644 --- a/mysql-test/main/derived_cond_pushdown.test +++ b/mysql-test/main/derived_cond_pushdown.test @@ -1,3 +1,4 @@ +--source include/have_sequence.inc --source include/default_optimizer_switch.inc let $no_pushdown= set statement optimizer_switch='condition_pushdown_for_derived=off' for; set @@join_buffer_size=256*1024; @@ -3328,4 +3329,46 @@ set join_cache_level=default; DROP TABLE t1,t2; + +--echo # +--echo # MDEV-21614: potentially splittable materialized derived/view +--echo # within materialized semi-join +--echo # + +create table t1 ( + id int not null auto_increment primary key, + a int not null +) engine=myisam; + +create table t2 ( + id int not null auto_increment primary key, + ro_id int not null, + flag int not null, key (ro_id) +) engine=myisam; + +insert into t1(a) select seq+100 from seq_1_to_20; +insert into t2(ro_id,flag) select seq, 1 from seq_1_to_20; +insert into t2(ro_id,flag) select seq, 0 from seq_1_to_20; + +create view v1 as +select t1.* from t1 left join t2 on (t1.id = t2.ro_id AND t2.flag = 1) + group by t1.id; + +let $q1= +select id, a from t1 where id in (select id from v1); +eval $q1; +eval explain extended $q1; + +let $q2= +select id, a from t1 + where id in (select id + from (select t1.* from t1 left join t2 + on (t1.id = t2.ro_id AND t2.flag = 1) + group by t1.id) dt); +eval $q2; +eval explain extended $q2; + +drop view v1; +drop table t1,t2; + --echo # End of 10.3 tests diff --git a/sql/opt_split.cc b/sql/opt_split.cc index cfac0c9..6f8248c 100644 --- a/sql/opt_split.cc +++ b/sql/opt_split.cc @@ -307,7 +307,7 @@ struct SplM_field_ext_info: public SplM_field_info 8. P contains some references on the columns of the joined tables C occurred also in the select list of this join 9. There are defined some keys usable for ref access of fields from C - with available statistics. + with available statistics. @retval true if the answer is positive @@ -477,6 +477,15 @@ bool JOIN::check_for_splittable_materialized() /* Attach this info to the table T */ derived->table->set_spl_opt_info(spl_opt_info); + /* + If this is specification of a materialized derived table T that is + potentially splittable and is used in the from list of the right operand + of an IN predicand transformed to a semi-join then the embedding semi-join + nest is not allowed to be materialized. + */ + if (derived && derived->is_materialized_derived() && + derived->embedding && derived->embedding->sj_subq_pred) + derived->embedding->sj_subq_pred->types_allow_materialization= FALSE; return true; }