mirror of
https://github.com/MariaDB/server.git
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Small semi-join optimization improvement:
- if we're considering FirstMatch access with one inner table, and @@optimizer_switch has semijoin_with_cache flag, calculate costs as if we used join cache (because we will be able to do so)
This commit is contained in:
Sergey Petrunya
parent
8e96081764
commit
ae480437ce
@ -5205,8 +5205,8 @@ INSERT INTO t2 VALUES (15,4);
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EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join)
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join)
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SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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pk i
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11 0
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@ -105,7 +105,7 @@ oref a
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1 1
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show status like '%Handler_read_rnd_next';
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Variable_name Value
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Handler_read_rnd_next 14
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Handler_read_rnd_next 5
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delete from t2;
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insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0);
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set optimizer_switch='subquery_cache=off';
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@ -1308,7 +1308,7 @@ insert into t1 select * from t0;
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explain select * from t0 where a in (select a from t1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join)
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select * from t0 where a in (select a from t1);
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a
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10.24
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@ -1321,7 +1321,7 @@ insert into t1 select * from t0;
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explain select * from t0 where a in (select a from t1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join)
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select * from t0 where a in (select a from t1);
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a
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2008-01-01
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@ -114,7 +114,7 @@ oref a
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1 1
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show status like '%Handler_read_rnd_next';
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Variable_name Value
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Handler_read_rnd_next 14
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Handler_read_rnd_next 5
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delete from t2;
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insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0);
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set optimizer_switch='subquery_cache=off';
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@ -1316,8 +1316,8 @@ create table t1 as select * from t0;
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insert into t1 select * from t0;
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explain select * from t0 where a in (select a from t1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY t1 hash_ALL NULL #hash#$hj 3 test.t0.a 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join)
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join)
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select * from t0 where a in (select a from t1);
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a
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10.24
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@ -1329,8 +1329,8 @@ create table t1 as select * from t0;
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insert into t1 select * from t0;
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explain select * from t0 where a in (select a from t1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY t1 hash_ALL NULL #hash#$hj 4 test.t0.a 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join)
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1 PRIMARY t0 ALL NULL NULL NULL NULL 2
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join)
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select * from t0 where a in (select a from t1);
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a
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2008-01-01
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@ -1230,16 +1230,16 @@ EXPLAIN
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SELECT * FROM t1 RIGHT JOIN t2 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 system NULL NULL NULL NULL 0 const row not found
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t1)
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using join buffer (flat, BNL join)
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t2); Using join buffer (flat, BNL join)
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SELECT * FROM t1 RIGHT JOIN t2 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2);
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c1 c1
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EXPLAIN
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SELECT * FROM t2 LEFT JOIN t1 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 system NULL NULL NULL NULL 0 const row not found
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t1)
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using join buffer (flat, BNL join)
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t2); Using join buffer (flat, BNL join)
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SELECT * FROM t2 LEFT JOIN t1 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2);
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c1 c1
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EXPLAIN
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@ -16,7 +16,7 @@ flush tables;
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EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; FirstMatch(OUTR); Using join buffer (flat, BNL join)
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flush tables;
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SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
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dt
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@ -24,7 +24,7 @@ flush tables;
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EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; FirstMatch(OUTR); Using join buffer (flat, BNL join)
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flush tables;
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SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
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dt
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@ -68,7 +68,7 @@ select * from t1
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where id in (select id from t1 as x1 where (t1.cur_date is null));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
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1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; FirstMatch(t1); Using join buffer (flat, BNL join)
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Warnings:
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Note 1276 Field or reference 'test.t1.cur_date' of SELECT #2 was resolved in SELECT #1
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Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`cur_date` AS `cur_date` from `test`.`t1` semi join (`test`.`t1` `x1`) where ((`test`.`x1`.`id` = `test`.`t1`.`id`) and (`test`.`t1`.`cur_date` = 0))
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@ -80,7 +80,7 @@ select * from t2
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where id in (select id from t2 as x1 where (t2.cur_date is null));
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where
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1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; FirstMatch(t2); Using join buffer (flat, BNL join)
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Warnings:
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Note 1276 Field or reference 'test.t2.cur_date' of SELECT #2 was resolved in SELECT #1
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Note 1003 select `test`.`t2`.`id` AS `id`,`test`.`t2`.`cur_date` AS `cur_date` from `test`.`t2` semi join (`test`.`t2` `x1`) where ((`test`.`x1`.`id` = `test`.`t2`.`id`) and (`test`.`t2`.`cur_date` = 0))
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@ -307,8 +307,7 @@ EXPLAIN SELECT 1 FROM t1 WHERE a IN
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(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 index PRIMARY,i2 PRIMARY 4 NULL 144 Using index
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
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2 MATERIALIZED t1 ALL NULL NULL NULL NULL 144
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1 PRIMARY t1 ALL NULL NULL NULL NULL 144 Using where; FirstMatch(t1); Using join buffer (flat, BNL join)
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CREATE TABLE t2 (a INT, b INT, KEY(a));
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INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);
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EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2;
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@ -432,7 +431,7 @@ WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t2 system NULL NULL NULL NULL 1
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1 PRIMARY t3 ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY <derived3> ALL NULL NULL NULL NULL 3 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY <derived3> ALL NULL NULL NULL NULL 3 Using where; FirstMatch(t3); Using join buffer (flat, BNL join)
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3 DERIVED t1 ALL NULL NULL NULL NULL 3
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SELECT * FROM t3
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WHERE t3.b IN (SELECT v1.b FROM v1, t2
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@ -5204,8 +5204,8 @@ INSERT INTO t2 VALUES (15,4);
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EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join)
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join)
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SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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pk i
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11 0
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@ -5209,8 +5209,8 @@ INSERT INTO t2 VALUES (15,4);
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EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join)
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary
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1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index
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1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join)
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SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1);
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pk i
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11 0
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@ -76,8 +76,7 @@ insert into t3 select a,a, a+100,a+100,a+100 from t0;
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explain select * from t3 where b in (select a from t1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t3 ALL b NULL NULL NULL 20
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 5 func 1
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2 MATERIALIZED t1 ALL NULL NULL NULL NULL 3
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where; FirstMatch(t3); Using join buffer (flat, BNL join)
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select * from t3 where b in (select a from t1);
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a b pk1 pk2 pk3
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1 1 1 1 1
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@ -979,10 +979,9 @@ FROM t1
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WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t2 ALL NULL NULL NULL NULL 18 100.00
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 8 func,func 1 100.00
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2 MATERIALIZED t1 ALL varchar_key NULL NULL NULL 15 100.00 Using where
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1 PRIMARY t1 ref varchar_key varchar_key 3 test.t2.varchar_nokey 2 100.00 Using where; FirstMatch(t2); Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
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Warnings:
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Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_key` < 'n') xor `test`.`t1`.`pk`))
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Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_key` = `test`.`t2`.`varchar_nokey`) and (`test`.`t1`.`varchar_nokey` = `test`.`t2`.`varchar_nokey`) and ((`test`.`t2`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`))
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SELECT varchar_nokey
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FROM t2
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WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
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@ -1061,10 +1060,8 @@ AND t1.val IN (SELECT t3.val FROM t3
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WHERE t3.val LIKE 'a%' OR t3.val LIKE 'e%');
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 5
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1 PRIMARY <subquery3> eq_ref distinct_key distinct_key 14 func 1
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 14 func 1
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3 MATERIALIZED t3 ALL NULL NULL NULL NULL 5 Using where
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2 MATERIALIZED t2 ALL NULL NULL NULL NULL 6 Using where
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1 PRIMARY t3 ALL NULL NULL NULL NULL 5 Using where; FirstMatch(t1); Using join buffer (flat, BNL join)
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1 PRIMARY t2 ALL NULL NULL NULL NULL 6 Using where; FirstMatch(t3); Using join buffer (incremental, BNL join)
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SELECT *
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FROM t1
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WHERE t1.val IN (SELECT t2.val FROM t2
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@ -1254,7 +1251,7 @@ A.t1field IN (SELECT C.t2field FROM t2 C
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WHERE C.t2field IN (SELECT D.t2field FROM t2 D));
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY A index PRIMARY PRIMARY 4 NULL 3 Using index
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1 PRIMARY B index NULL PRIMARY 4 NULL 3 Using index; Start temporary; End temporary; Using join buffer (flat, BNL join)
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1 PRIMARY B index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(A); Using join buffer (flat, BNL join)
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1 PRIMARY C eq_ref PRIMARY PRIMARY 4 test.A.t1field 1 Using index
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1 PRIMARY D eq_ref PRIMARY PRIMARY 4 test.A.t1field 1 Using index
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SELECT * FROM t1 A
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@ -1283,11 +1280,9 @@ select * from t1 A, t1 B
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where A.a = B.a and A.a in (select a from t2 C) and B.a in (select a from t2 D);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY A ALL NULL NULL NULL NULL 3
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 5 func 1
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1 PRIMARY B ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
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1 PRIMARY <subquery3> eq_ref distinct_key distinct_key 5 func 1
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2 MATERIALIZED C ALL NULL NULL NULL NULL 3
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3 MATERIALIZED D ALL NULL NULL NULL NULL 3
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1 PRIMARY C ALL NULL NULL NULL NULL 3 Using where; FirstMatch(B); Using join buffer (incremental, BNL join)
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1 PRIMARY D ALL NULL NULL NULL NULL 3 Using where; FirstMatch(C); Using join buffer (incremental, BNL join)
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drop table t1, t2;
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#
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# BUG#784441: Abort on semijoin with a view as the inner table
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@ -2160,8 +2155,8 @@ SELECT * FROM t1, t2
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WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 2
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1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); Start temporary
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1 PRIMARY t2 hash_ALL PRIMARY #hash#PRIMARY 4 test.t3.b 4 End temporary; Using join buffer (flat, BNLH join)
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1 PRIMARY t2 ALL PRIMARY NULL NULL NULL 4 Using join buffer (flat, BNL join)
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1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); FirstMatch(t2)
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SELECT * FROM t1, t2
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WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a);
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a a b
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@ -2175,8 +2170,8 @@ SELECT * FROM t1, t2
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WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 2
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1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); Start temporary
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1 PRIMARY t2 eq_ref PRIMARY PRIMARY 4 test.t3.b 1 End temporary; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
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1 PRIMARY t2 ALL PRIMARY NULL NULL NULL 4 Using join buffer (flat, BNL join)
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1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); FirstMatch(t2)
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SELECT * FROM t1, t2
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WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a);
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a a b
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@ -2617,13 +2617,27 @@ bool Firstmatch_picker::check_qep(JOIN *join,
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!(firstmatch_need_tables & remaining_tables))
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{
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/*
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Got a complete FirstMatch range.
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Calculate correct costs and fanout
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Got a complete FirstMatch range. Calculate correct costs and fanout
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*/
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optimize_wo_join_buffering(join, first_firstmatch_table, idx,
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remaining_tables, FALSE, idx,
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record_count,
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read_time);
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if (idx == first_firstmatch_table &&
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optimizer_flag(join->thd, OPTIMIZER_SWITCH_SEMIJOIN_WITH_CACHE))
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{
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/*
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An important special case: only one inner table, and @@optimizer_switch
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allows join buffering.
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- read_time is the same (i.e. FirstMatch doesn't add any cost
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- remove fanout added by the last table
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*/
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*record_count /= join->positions[idx].records_read;
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}
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else
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{
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optimize_wo_join_buffering(join, first_firstmatch_table, idx,
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remaining_tables, FALSE, idx,
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record_count,
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read_time);
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}
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/*
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We ought to save the alternate POSITIONs produced by
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optimize_wo_join_buffering but the problem is that providing save
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