Could it be of use for the INSERT ... SELECT ... queries?
Sergei Petrunia <[email protected]> wrote: >Hi, > >Among the topics of yesterday's optimizer call was the question of what >is the >point of EXPLAIN INSERT. The point was that INSERT doesn't need a query >plan. >Somebody has mentioned that perhaps, EXPLAIN INSERT could show results >of >partition pruning. > >This doesn't seem to be the case: > > >5.6.14-debug >MySQL [test]> explain partitions insert into t1p values (2,2); >+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------------+ >| id | select_type | table | partitions | type | possible_keys | key | >key_len | ref | rows | Extra | >+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------------+ >| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | >NULL | NULL | NULL | No tables used | >+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------------+ >1 row in set (1.34 sec) > > >5.7.2-m12-debug: >MySQL [test]> explain partitions insert into t1p values (1,1); >+----+-------------+-------+-------------+------+---------------+------+---------+------+------+-------+ >| id | select_type | table | partitions | type | possible_keys | key >| key_len | ref | rows | Extra | >+----+-------------+-------+-------------+------+---------------+------+---------+------+------+-------+ >| 1 | INSERT | t1p | p0,p1,p2,p3 | ALL | NULL | NULL >| NULL | NULL | NULL | NULL | >+----+-------------+-------+-------------+------+---------------+------+---------+------+------+-------+ >1 row in set (0.00 sec) > > >That is, EXPLAIN in 5.7 looks a bit more meaningful, but it still >doesn't show >results of partition pruning. > >The table t1p is partitioned, it was created as follows: > >create table t1(a int); >insert into t1 values (1),(2),(3),(4); >create table t1p (a int, b int) partition by hash(a) partitions 4; >insert into t1p select * from t1; > >that is, values (1,1) should have allowed to pick the partition to use, >or it >wasn't done. > >So, is EXPLAIN INSERT meaningles, or I am missing something here? > > >BR > Sergei >-- > >Sergei Petrunia, Software Developer >MariaDB | Skype: sergefp | Blog: http://s.petrunia.net/blog > > > >_______________________________________________ >Mailing list: https://launchpad.net/~maria-developers >Post to : [email protected] >Unsubscribe : https://launchpad.net/~maria-developers >More help : https://help.launchpad.net/ListHelp
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