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MDEV-24936 EXPLAIN for query based on table value constructor lacks info

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on used subqueries

If a query was based on a table value constructor that contained subqueries
then EXPLAIN for such query did not contain any lines explaining the
execution plans of the subqueries.
This happened because
- no optimize() method was called for any subquery used by the table value
  constructor when EXPLAIN command for the query was processed;
- EXPLAIN node created for the table value constructor itself did not
  assume that some child nodes could be attached to it.

Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2021-02-21 22:01:24 -08:00
parent a49ce0bf93
commit a5b18613ec
3 changed files with 72 additions and 2 deletions
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33
mysql-test/main/table_value_constr.result
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@ -2742,4 +2742,37 @@ NULL UNION RESULT <union4,5> ALL NULL NULL NULL NULL NULL NULL
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <nop>(<in_optimizer>(`test`.`t1`.`a`,<min>(/* select#4 */ select `tvc_0`.`7` from (values (7)) `tvc_0` union /* select#5 */ select `tvc_0`.`8` from (values (8)) `tvc_0`) <= <cache>(`test`.`t1`.`a`)))
drop table t1;
#
# MDEV-24934:EXPLAIN for queries based on TVC using subqueries
#
create table t1 (a int);
insert into t1 values (3), (7), (1);
values (8), ((select * from t1 where a between 2 and 4));
8
8
3
explain values (8), ((select * from t1 where a between 2 and 4));
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
2 SUBQUERY t1 ALL NULL NULL NULL NULL 3 Using where
values ((select * from t1 where a between 2 and 4)),
((select * from t1 where a > 10));
(select * from t1 where a between 2 and 4)
3
NULL
explain values ((select * from t1 where a between 2 and 4)),
((select * from t1 where a > 10));
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
3 SUBQUERY t1 ALL NULL NULL NULL NULL 3 Using where
2 SUBQUERY t1 ALL NULL NULL NULL NULL 3 Using where
values (10,11), ((select * from t1 where a = 7) + 1, 21);
10 11
10 11
8 21
explain values (10,11), ((select * from t1 where a = 7) + 1, 21);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
2 SUBQUERY t1 ALL NULL NULL NULL NULL 3 Using where
drop table t1;
End of 10.3 tests