1853 lines
134 KiB
Plaintext
1853 lines
134 KiB
Plaintext
# WL#8244 Hints for subquery execution
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CREATE TABLE t1 (a INTEGER NOT NULL, b INT, PRIMARY KEY (a));
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CREATE TABLE t2 (a INTEGER NOT NULL, KEY (a));
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CREATE TABLE t3 (a INTEGER NOT NULL, b INT, KEY (a));
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INSERT INTO t1 VALUES (1,10), (2,20), (3,30), (4,40);
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INSERT INTO t2 VALUES (2), (3), (4), (5);
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INSERT INTO t3 VALUES (10,3), (20,4), (30,5);
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ANALYZE TABLE t1, t2, t3;
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Table Op Msg_type Msg_text
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test.t1 analyze status OK
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test.t2 analyze status OK
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test.t3 analyze status OK
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This query will normally use Table Pull-out
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EXPLAIN
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SELECT * FROM t2 WHERE t2.a IN (SELECT a FROM t1);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
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1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
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Check that we can disable SEMIJOIN transformation
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EXPLAIN
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SELECT * FROM t2 WHERE t2.a IN (SELECT /*+ NO_SEMIJOIN() */ a FROM t1);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
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2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#2`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
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Same with hint in outer query
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
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2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
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Query with two sub-queries
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EXPLAIN
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SELECT * FROM t3
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WHERE t3.a IN (SELECT a FROM t1 tx)
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AND t3.b IN (SELECT a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
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1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
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1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and (`test`.`tx`.`a` = `test`.`t3`.`a`))
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No SEMIJOIN transformation for first subquery
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EXPLAIN
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SELECT * FROM t3
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WHERE t3.a IN (SELECT /*+ NO_SEMIJOIN() */ a FROM t1 tx)
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AND t3.b IN (SELECT a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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1 PRIMARY ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
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2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))))
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(`subq1`) */ a FROM t1 tx)
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AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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1 PRIMARY ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
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2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))))
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No SEMIJOIN transformation for latter subquery
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EXPLAIN
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SELECT * FROM t3
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WHERE t3.a IN (SELECT a FROM t1 tx)
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AND t3.b IN (SELECT /*+ NO_SEMIJOIN() */ a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
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1 PRIMARY tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#3`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@`subq2`) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
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AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
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1 PRIMARY tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
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No SEMIJOIN transformation for any subquery
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EXPLAIN
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SELECT * FROM t3
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WHERE t3.a IN (SELECT /*+ NO_SEMIJOIN() */ a FROM t1 tx)
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AND t3.b IN (SELECT /*+ NO_SEMIJOIN() */ a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#2`) NO_SEMIJOIN(@`select#3`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where (<in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1) NO_SEMIJOIN(@subq2) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
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AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1`) NO_SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where (<in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
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Query with nested sub-queries
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EXPLAIN
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SELECT * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
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WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
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1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
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1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.tx.b 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and (`test`.`ty`.`a` = `test`.`tx`.`b`))
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No SEMIJOIN transformation for outer subquery
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
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WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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2 DEPENDENT SUBQUERY tx NULL eq_ref PRIMARY PRIMARY 4 func 1 100.00 Using where
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2 DEPENDENT SUBQUERY ty NULL eq_ref PRIMARY PRIMARY 4 test.tx.b 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq1`) */ 1 from `test`.`t1` `ty` join `test`.`t1` `tx` where ((`test`.`ty`.`a` = `test`.`tx`.`b`) and (<cache>(`test`.`t3`.`a`) = `test`.`tx`.`a`))))
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No SEMIJOIN transformation for inner-most subquery
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq2) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
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WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
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1 PRIMARY tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`tx`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`tx`.`b`) in t1 on PRIMARY))))
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No SEMIJOIN transformation at all
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1) NO_SEMIJOIN(@subq2) */ * FROM t3
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WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
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WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
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2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using where
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3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) NO_SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY where <in_optimizer>(`test`.`tx`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`tx`.`b`) in t1 on PRIMARY))))))
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This query does not support SEMIJOIN. SEMIJOIN hint is ignored
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EXPLAIN
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SELECT /*+ SEMIJOIN(@subq) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ min(a) FROM t1 group by a);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
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2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ min(`test`.`t1`.`a`) from `test`.`t1` group by `test`.`t1`.`a` having true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`min(a)`)))))
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This query will get LooseScan by default
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EXPLAIN
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SELECT * FROM t2 WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
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1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
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Let's turn off LooseScan, FirstMatch is then SELECTed
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
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1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
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Let's also turn off FirstMatch, MatLookup is then used
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using where; Using index
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1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t2.a 1 100.00 NULL
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2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`<subquery2>`.`a` = `test`.`t2`.`a`)
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Let's also turn off Materialization, DuplicateWeedout should then be used
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN, MATERIALIZATION) */ *
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FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
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1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
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If we turn off all strategies, DuplicateWeedout should still be used
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN, MATERIALIZATION,
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DUPSWEEDOUT) */ *
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FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
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1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
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Turn off non-used strategies, nothing should change. Still Loosescan
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EXPLAIN
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SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ *
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FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
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1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
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Test same query with SEMIJOIN hint
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Forcing LooseScan, should not change anything
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EXPLAIN
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SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
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1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
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Warnings:
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Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
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Force FirstMatch
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EXPLAIN
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SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
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1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
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Warnings:
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Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
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Force Materialization
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EXPLAIN
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SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION) */ * FROM t2
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WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
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id select_type table partitions type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using where; Using index
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t2.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`<subquery2>`.`a` = `test`.`t2`.`a`)
|
|
Force DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
If LooseScan is among candidates, it will be used
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH, MATERIALIZATION,
|
|
DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Drop LooseScan from list of strategies, FirstMatch will be used
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
|
|
Drop FirstMatch, MatLookup is next
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using where; Using index
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t2.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`<subquery2>`.`a` = `test`.`t2`.`a`)
|
|
For this query LooseScan and Materialization is not applicable
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.b 1 33.33 Using where; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t3`.`b` = `test`.`t1`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`b`))
|
|
Turn off all applicable strategies. DuplicateWeedout should be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Similar with SEMIJOIN hint
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Test multiple subqueries.
|
|
Default for this query is Loosecan for first and FirstMatch for latter
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Forcing the default strategy should not change anything
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) SEMIJOIN(@`subq2` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Forcing a strategy for one, may change the other due to cost changes
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Forcing same strategy for both
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t3)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) SEMIJOIN(@`subq2` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Loosescan for both is not possible, ends up with DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) SEMIJOIN(@subq2 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) SEMIJOIN(@`subq2` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Swap strategies compared to default
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) SEMIJOIN(@subq2 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) SEMIJOIN(@`subq2` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Different subsets of strategies for different subqueries
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN)
|
|
SEMIJOIN(@subq2 MATERIALIZATION, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) SEMIJOIN(@`subq2` MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Vice versa
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION, DUPSWEEDOUT)
|
|
SEMIJOIN(@subq2 FIRSTMATCH, LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION, DUPSWEEDOUT) SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
Another combination
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION, FIRSTMATCH)
|
|
SEMIJOIN(@subq2 LOOSESCAN, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION) SEMIJOIN(@`subq2` LOOSESCAN, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Turn off default
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Also turn off 2nd choice. Gives DuplicateWeedout over both
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Also turn off DuplicateWeedout. Materialization is only one left.
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH, DUPSWEEDOUT)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
Force materialization with SEMIJOIN hints instead
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION)
|
|
SEMIJOIN(@subq2 MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) SEMIJOIN(@`subq2` MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
This query gives DuplicateWeedout over both since combining
|
|
DuplicateWeedout with another strategy does not seem possible.
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION)
|
|
SEMIJOIN(@subq2 DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) SEMIJOIN(@`subq2` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
More alternatives for 2nd subquery gives Materialization for first
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION)
|
|
SEMIJOIN(@subq2 LOOSESCAN, FIRSTMATCH, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
A query with nested subqueries which by default will use FirstMatch
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Let's turn off FirstMatch, Materialization is then selected
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 MATERIALIZED t2 NULL ref a a 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `<subquery2>`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Let's also turn off Materialization, DuplicateWeedout is then used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Also turn off DuplicateWeedout. LooseScan not usable; so still DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
If we turn off all strategies, DuplicateWeedout should still be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN, MATERIALIZATION,
|
|
DUPSWEEDOUT) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Test same query with SEMIJOIN hint
|
|
Force FirstMatch, should not change anything
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Force LooseScan, will use DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Force Materialization
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 MATERIALIZED t2 NULL ref a a 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `<subquery2>`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Force DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
If FirstMatch is among candidates, it will be used
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, LOOSESCAN,
|
|
DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Drop FirstMatch. Materialization will be used
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION, LOOSESCAN, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 MATERIALIZED t2 NULL ref a a 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `<subquery2>`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Drop Materialization, DuplicateWeedout next
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 NULL
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Strategy hints on inner-most query is ignored since sj-nests are merged
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Ditto
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq2 MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2` MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3` join `test`.`t2`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`b`))
|
|
Turn off semijoin for outer subquery. FirstMatch is used for inner
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 DEPENDENT SUBQUERY t3 NULL ref a a 4 func 1 100.00 Using where
|
|
2 DEPENDENT SUBQUERY t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; FirstMatch(t3)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq1`) */ 1 from `test`.`t3` semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t3`.`b`) and (<cache>(`test`.`t1`.`a`) = `test`.`t3`.`a`))))
|
|
Do not use FirstMatch for inner
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1) NO_SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 SUBQUERY <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t3.b 1 100.00 NULL
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2` FIRSTMATCH) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`<subquery3>`.`a` = `test`.`t3`.`b`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
Do not use FirstMatch nor Materialization for inner
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 SUBQUERY t2 NULL ref a a 4 test.t3.b 1 100.00 Using index; Start temporary; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2` FIRSTMATCH, MATERIALIZATION) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`test`.`t2`.`a` = `test`.`t3`.`b`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
LooseScan is last resort
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`test`.`t3`.`b` = `test`.`t2`.`a`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
Allow all stragies except default
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1)
|
|
SEMIJOIN(@subq2 MATERIALIZATION, DUPSWEEDOUT, LOOSESCAN) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
2 SUBQUERY <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t3.b 1 100.00 NULL
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2` LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`<subquery3>`.`a` = `test`.`t3`.`b`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
Force a particular strategy
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1) SEMIJOIN(@subq2 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2` LOOSESCAN) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`test`.`t3`.`b` = `test`.`t2`.`a`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
Turn off semijoin for inner-most subquery. FirstMatch is used for outer
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 NULL
|
|
1 PRIMARY t3 NULL ref a a 4 test.t1.a 1 100.00 Using where; FirstMatch(t1)
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t3`.`a` = `test`.`t1`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
Do not use FirstMatch for outer
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH) NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 PRIMARY <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) NO_SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`a` = `test`.`t1`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
Do not use FirstMatch nor Materialization for outer
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION)
|
|
NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 PRIMARY t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 End temporary
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
LooseScan can not be used since index scan would not be "covering"
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT)
|
|
NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 PRIMARY t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 End temporary
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
Allow all stragies except default
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION, DUPSWEEDOUT, LOOSESCAN)
|
|
NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 PRIMARY <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`a` = `test`.`t1`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
Force a particular strategy
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 DUPSWEEDOUT) NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 PRIMARY t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 End temporary
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) SEMIJOIN(@`subq1` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))
|
|
Turn off semijoin for both subqueries
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1) NO_SEMIJOIN(@subq2) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 DEPENDENT SUBQUERY t3 NULL index_subquery a a 4 func 1 100.00 Using where
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2`) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,<exists>(<index_lookup>(<cache>(`test`.`t1`.`a`) in t3 on a where <in_optimizer>(`test`.`t3`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t3`.`b`) in t2 on a))))))
|
|
Test hints with prepared statements
|
|
PREPARE stmt1 FROM "EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2)";
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
DEALLOCATE PREPARE stmt1;
|
|
Another Prepared Statement test
|
|
PREPARE stmt1 FROM "EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1) SEMIJOIN(@subq2 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3
|
|
WHERE t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2))";
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2` LOOSESCAN) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`test`.`t3`.`b` = `test`.`t2`.`a`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
2 SUBQUERY t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
2 SUBQUERY t3 NULL ALL a NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2` LOOSESCAN) NO_SEMIJOIN(@`subq1`) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` semi join (`test`.`t2`) where (`test`.`t3`.`b` = `test`.`t2`.`a`) ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`)))))
|
|
DEALLOCATE PREPARE stmt1;
|
|
SET optimizer_switch = default;
|
|
Tests with non-default optimizer_switch settings
|
|
SET optimizer_switch = 'semijoin=off';
|
|
No table pull-out for this query
|
|
EXPLAIN
|
|
SELECT * FROM t2 WHERE t2.a IN (SELECT a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
This should not change anything
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Force semijoin
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
Setting strategy should still force semijoin
|
|
Strategy is ignored since table pull-out is done
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq FIRSTMATCH) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq` FIRSTMATCH) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
Query with two sub-queries
|
|
EXPLAIN
|
|
SELECT * FROM t3
|
|
WHERE t3.a IN (SELECT a FROM t1 tx)
|
|
AND t3.b IN (SELECT a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where (<in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
|
|
SEMIJOIN transformation for first subquery
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
1 PRIMARY tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
|
|
3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`t3`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`b`) in t1 on PRIMARY))))
|
|
SEMIJOIN transformation for latter subquery
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq2) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
1 PRIMARY ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
|
|
2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))))
|
|
SEMIJOIN transformation for both subqueries
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1) SEMIJOIN(@subq2) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
|
|
1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1`) SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and (`test`.`tx`.`a` = `test`.`t3`.`a`))
|
|
Query with nested sub-queries
|
|
EXPLAIN
|
|
SELECT * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using where
|
|
3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY where <in_optimizer>(`test`.`tx`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`tx`.`b`) in t1 on PRIMARY))))))
|
|
SEMIJOIN transformation for outer subquery
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
1 PRIMARY tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and <in_optimizer>(`test`.`tx`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`tx`.`b`) in t1 on PRIMARY))))
|
|
SEMIJOIN transformation for inner-most subquery
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq2) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
2 DEPENDENT SUBQUERY tx NULL eq_ref PRIMARY PRIMARY 4 func 1 100.00 Using where
|
|
2 DEPENDENT SUBQUERY ty NULL eq_ref PRIMARY PRIMARY 4 test.tx.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq1`) */ 1 from `test`.`t1` `ty` join `test`.`t1` `tx` where ((`test`.`ty`.`a` = `test`.`tx`.`b`) and (<cache>(`test`.`t3`.`a`) = `test`.`tx`.`a`))))
|
|
SEMIJOIN transformation for both
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1) SEMIJOIN(@subq2) */ * FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.tx.b 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq2`) SEMIJOIN(@`subq1`) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`tx`.`a` = `test`.`t3`.`a`) and (`test`.`ty`.`a` = `test`.`tx`.`b`))
|
|
Test strategies when some are disabled by optimizer_switch
|
|
SET optimizer_switch='semijoin=on';
|
|
SET optimizer_switch='loosescan=off';
|
|
This query will get LooseScan by default. FirstMatch now.
|
|
EXPLAIN
|
|
SELECT * FROM t2 WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
|
|
Let's turn off LooseScan also by hint, FirstMatch should still be SELECTed
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
|
|
Let's also turn off FirstMatch, MatLookup should then be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using where; Using index
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t2.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`<subquery2>`.`a` = `test`.`t2`.`a`)
|
|
Let's also turn off Materialization, DuplicateWeedout should then be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION) */ *
|
|
FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Let's force LooseScan back on
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Forcing another strategy
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using where; Using index
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t2.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`<subquery2>`.`a` = `test`.`t2`.`a`)
|
|
If LooseScan is among candidates, it is used even if originally disabled
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH, MATERIALIZATION,
|
|
DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Disable another strategy
|
|
SET optimizer_switch='firstmatch=off';
|
|
Turn on FirstMatch, but not LooseScan on with hint
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
|
|
Drop all remaining strategies with hint, should use DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 MATERIALIZATION, DUPSWEEDOUT) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
For this query LooseScan and Materialization is not applicable
|
|
Should use DuplicateWeedout since FirstMatch is disabled
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 25.00 Using where; End temporary
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t3`.`b`) and (`test`.`t1`.`b` = `test`.`t3`.`a`))
|
|
Turn off all applicable strategies. DuplicateWeedout should still be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Reverse which strategies are allowed with hint
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.b 1 33.33 Using where; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t3`.`b` = `test`.`t1`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`b`))
|
|
Default for this query is Loosecan for first and FirstMatch for latter
|
|
Since both strategies are disabled, will now use DuplicateWeedout
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Allowing LooseScan and FirstMatch and optimizer_switch is ignored
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH)
|
|
SEMIJOIN(@subq2 LOOSESCAN, FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Forcing a disabled strategy for one
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; End temporary; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Forcing same strategy for both
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t3)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) SEMIJOIN(@`subq2` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Swap strategies compared to default
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH) SEMIJOIN(@subq2 LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH) SEMIJOIN(@`subq2` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Different subsets of strategies for different subqueries
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN)
|
|
SEMIJOIN(@subq2 MATERIALIZATION, DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) SEMIJOIN(@`subq2` MATERIALIZATION, DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
Turn off DuplicateWeedout for both. Materialization is left
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 DUPSWEEDOUT)
|
|
NO_SEMIJOIN(@subq2 DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` DUPSWEEDOUT) NO_SEMIJOIN(@`subq2` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
Forcing materialization should have same effect
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 MATERIALIZATION)
|
|
SEMIJOIN(@subq2 MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` MATERIALIZATION) SEMIJOIN(@`subq2` MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
Turn off DuplicateWeedout for first. Materialization is used for both
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
Turn off DuplicateWeedout for second. Same effect.
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq2 DUPSWEEDOUT) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery3> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.a 1 100.00 NULL
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq2` DUPSWEEDOUT) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `<subquery3>`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`a`))
|
|
Enable all strategies except DuplicateWeedout
|
|
SET optimizer_switch='firstmatch=on,loosescan=on,materialization=on,duplicateweedout=off';
|
|
If we turn off all other strategies, DuplicateWeedout will be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH, MATERIALIZATION) */ *
|
|
FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN, MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
LooseScan and Materialization is not applicable, FirstMatch is used
|
|
EXPLAIN
|
|
SELECT * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.b 1 33.33 Using where; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t3`.`b` = `test`.`t1`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`b`))
|
|
Turn off all applicable strategies. DuplicateWeedout should be used
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Similar with SEMIJOIN hint
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Disable all strategies
|
|
SET optimizer_switch='firstmatch=off,loosescan=off,materialization=off,duplicateweedout=off';
|
|
DuplicateWeedout is then used
|
|
EXPLAIN
|
|
SELECT * FROM t2 WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Turning off extra strategies should not change anything
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN, DUPSWEEDOUT) */ *
|
|
FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t2 NULL ref a a 4 test.t3.a 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN, DUPSWEEDOUT) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t2`.`a` = `test`.`t3`.`a`)
|
|
Turning on some strategies should give one of those
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 FIRSTMATCH, MATERIALIZATION) */ *
|
|
FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t3 NULL ref a a 4 test.t2.a 1 100.00 Using index; FirstMatch(t2)
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t3`) where (`test`.`t3`.`a` = `test`.`t2`.`a`)
|
|
For this query that cannot use LooseScan or Materialization,
|
|
turning those on will still give DupliateWeedout
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, MATERIALIZATION) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE <subquery2> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 9 test.t1.b,test.t1.a 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL ALL a NULL NULL NULL 3 100.00 NULL
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN, MATERIALIZATION) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`<subquery2>`.`b` = `test`.`t1`.`a`) and (`<subquery2>`.`a` = `test`.`t1`.`b`))
|
|
Turning on FirstMatch should give FirstMatch
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN, FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.b IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3 WHERE t3.b = t1.a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.b 1 33.33 Using where; FirstMatch(t1)
|
|
Warnings:
|
|
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) where ((`test`.`t3`.`b` = `test`.`t1`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`b`))
|
|
SET optimizer_switch = default;
|
|
Test that setting optimizer_switch after prepare will change strategy
|
|
PREPARE stmt1 FROM "EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 FIRSTMATCH, LOOSESCAN)
|
|
NO_SEMIJOIN(@subq2 FIRSTMATCH, LOOSESCAN) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2)";
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
SET optimizer_switch = 'duplicateweedout=off';
|
|
Will now use materialization
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE <subquery2> NULL ALL NULL NULL NULL NULL NULL 100.00 NULL
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 <subquery2>.a 1 100.00 Using where
|
|
1 SIMPLE <subquery3> NULL eq_ref <auto_distinct_key> <auto_distinct_key> 4 test.t1.b 1 100.00 NULL
|
|
2 MATERIALIZED t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
3 MATERIALIZED t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`<subquery3>`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `<subquery2>`.`a`))
|
|
SET optimizer_switch = 'duplicateweedout=on';
|
|
Turn DuplicateWeedout back on
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; Start temporary
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; End temporary
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` FIRSTMATCH, LOOSESCAN) NO_SEMIJOIN(@`subq2` FIRSTMATCH, LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
DEALLOCATE PREPARE stmt1;
|
|
SET optimizer_switch = default;
|
|
Specifying two SEMIJOIN/NO_SEMIJOIN for same query block gives warning
|
|
First has effect, second is ignored
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ NO_SEMIJOIN() SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN( ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#2`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Try opposite order
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ SEMIJOIN() NO_SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint NO_SEMIJOIN( ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`select#2`) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
Specify at different levels, hint inside block has effect
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint NO_SEMIJOIN(@`subq` ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
Specify at different levels, opposite order
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) NO_SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq` ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Duplicate hints also gives warning, but hint has effect
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq` ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) NO_SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint NO_SEMIJOIN(@`subq` ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Multiple subqueries with conflicting hints
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) NO_SEMIJOIN() */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) SEMIJOIN(LOOSESCAN) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
2 SUBQUERY t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq1` LOOSESCAN) is ignored as conflicting/duplicated
|
|
Warning 3126 Hint SEMIJOIN(@`subq2` FIRSTMATCH) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1`) SEMIJOIN(@`subq2` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` where true ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`))))))
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) SEMIJOIN(@subq2 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) NO_SEMIJOIN(LOOSESCAN) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) SEMIJOIN(LOOSESCAN) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq1` LOOSESCAN) is ignored as conflicting/duplicated
|
|
Warning 3126 Hint SEMIJOIN(@`subq2` FIRSTMATCH) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN) SEMIJOIN(@`subq2` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Conflicting hints in same hint comment
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) SEMIJOIN(@subq1 FIRSTMATCH) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq1` FIRSTMATCH) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 LOOSESCAN) NO_SEMIJOIN(@subq1 LOOSESCAN) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Warning 3126 Hint NO_SEMIJOIN(@`subq1` LOOSESCAN) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
EXPLAIN
|
|
SELECT /*+ NO_SEMIJOIN(@subq1 LOOSESCAN) NO_SEMIJOIN(@subq1 FIRSTMATCH) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL ALL PRIMARY NULL NULL NULL 4 25.00 Using where; Using join buffer (Block Nested Loop)
|
|
1 SIMPLE t3 NULL ref a a 4 test.t1.a 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Warning 3126 Hint NO_SEMIJOIN(@`subq1` FIRSTMATCH) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq1` LOOSESCAN) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t1`.`b` = `test`.`t2`.`a`) and (`test`.`t3`.`a` = `test`.`t1`.`a`))
|
|
Non-supported strategies should give warnings
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq1 INTOEXISTS) NO_SEMIJOIN(@subq2 INTOEXISTS) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL index a a 4 NULL 3 100.00 Using index; LooseScan
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using where
|
|
1 SIMPLE t2 NULL ref a a 4 test.t1.b 1 100.00 Using index; FirstMatch(t1)
|
|
Warnings:
|
|
Warning 1064 Optimizer hint syntax error near 'INTOEXISTS) NO_SEMIJOIN(@subq2 INTOEXISTS) */ *
|
|
FROM t1
|
|
WHERE t1.a IN (SELECT /*' at line 2
|
|
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` semi join (`test`.`t3`) semi join (`test`.`t2`) where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t1`.`a` = `test`.`t3`.`a`))
|
|
SUBQUERY tests
|
|
SUBQUERY should disable SEMIJOIN and use specified subquery strategy
|
|
EXPLAIN
|
|
SELECT * FROM t2 WHERE t2.a IN (SELECT /*+ SUBQUERY(INTOEXISTS) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`select#2` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`)))))
|
|
Query with two subqueries
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 INTOEXISTS) SUBQUERY(@subq2 MATERIALIZATION) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
3 SUBQUERY ty NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq1` INTOEXISTS) SUBQUERY(@`subq2` MATERIALIZATION) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where (<in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY))) and <in_optimizer>(`test`.`t3`.`b`,`test`.`t3`.`b` in ( <materialize> (/* select#3 */ select /*+ QB_NAME(`subq2`) */ `test`.`ty`.`a` from `test`.`t1` `ty` where true ), <primary_index_lookup>(`test`.`t3`.`b` in <temporary table> on <auto_distinct_key> where ((`test`.`t3`.`b` = `materialized-subquery`.`a`))))))
|
|
Query with nested sub-queries
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 INTOEXISTS) SUBQUERY(@subq2 MATERIALIZATION) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
2 DEPENDENT SUBQUERY tx NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using where
|
|
3 SUBQUERY ty NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq2` MATERIALIZATION) SUBQUERY(@`subq1` INTOEXISTS) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t3`.`a`) in t1 on PRIMARY where <in_optimizer>(`test`.`tx`.`b`,`test`.`tx`.`b` in ( <materialize> (/* select#3 */ select /*+ QB_NAME(`subq2`) */ `test`.`ty`.`a` from `test`.`t1` `ty` where true ), <primary_index_lookup>(`test`.`tx`.`b` in <temporary table> on <auto_distinct_key> where ((`test`.`tx`.`b` = `materialized-subquery`.`a`))))))))
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 MATERIALIZATION) SUBQUERY(@subq2 INTOEXISTS) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx
|
|
WHERE tx.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty));
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t3 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
|
|
2 SUBQUERY tx NULL ALL PRIMARY NULL NULL NULL 4 100.00 Using where
|
|
3 DEPENDENT SUBQUERY ty NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq2` INTOEXISTS) SUBQUERY(@`subq1` MATERIALIZATION) */ `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,`test`.`t3`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`tx`.`a` from `test`.`t1` `tx` where <in_optimizer>(`test`.`tx`.`b`,<exists>(<primary_index_lookup>(<cache>(`test`.`tx`.`b`) in t1 on PRIMARY))) ), <primary_index_lookup>(`test`.`t3`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t3`.`a` = `materialized-subquery`.`a`)))))
|
|
This query does not support SEMIJOIN. Materialization is default
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ min(a) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ min(`test`.`t1`.`a`) from `test`.`t1` group by `test`.`t1`.`a` having true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`min(a)`)))))
|
|
Use In-to-exists instead
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq INTOEXISTS) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ min(a) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq`) */ 1 from `test`.`t1` group by `test`.`t1`.`a` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(min(`test`.`t1`.`a`)))))
|
|
For this query In-to-exists is default
|
|
EXPLAIN
|
|
SELECT a, a IN (SELECT a FROM t1) FROM t2;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY))) AS `a IN (SELECT a FROM t1)` from `test`.`t2`
|
|
Force Subquery Materialization
|
|
EXPLAIN
|
|
SELECT a, a IN (SELECT /*+ SUBQUERY(MATERIALIZATION) */ a FROM t1) FROM t2;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`select#2` MATERIALIZATION) */ `test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`))))) AS `a IN (SELECT /*+ SUBQUERY(MATERIALIZATION) */ a FROM t1)` from `test`.`t2`
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ a,
|
|
a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1) FROM t2;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` MATERIALIZATION) */ `test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`))))) AS `a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1)` from `test`.`t2`
|
|
This query does not support Subquery Materialization due to type mismatch
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ sum(b) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 NULL
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq`) */ 1 from `test`.`t1` group by `test`.`t1`.`a` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(sum(`test`.`t1`.`b`)))))
|
|
Trying to force Subquery Materialization will not change anything
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ sum(b) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 NULL
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq`) */ 1 from `test`.`t1` group by `test`.`t1`.`a` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(sum(`test`.`t1`.`b`)))))
|
|
Test hints with prepared statements
|
|
PREPARE stmt1 FROM "EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 MATERIALIZATION)
|
|
SUBQUERY(@subq2 INTOEXISTS) */ * FROM t1
|
|
WHERE t1.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t3)
|
|
AND t1.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t2)";
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
2 SUBQUERY t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq1` MATERIALIZATION) SUBQUERY(@`subq2` INTOEXISTS) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` where true ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`))))) and <in_optimizer>(`test`.`t1`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t1`.`b`) in t2 on a))))
|
|
EXECUTE stmt1;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
|
|
3 DEPENDENT SUBQUERY t2 NULL index_subquery a a 4 func 1 100.00 Using index
|
|
2 SUBQUERY t3 NULL index a a 4 NULL 3 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq1` MATERIALIZATION) SUBQUERY(@`subq2` INTOEXISTS) */ `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq1`) */ `test`.`t3`.`a` from `test`.`t3` where true ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t1`.`a` = `materialized-subquery`.`a`))))) and <in_optimizer>(`test`.`t1`.`b`,<exists>(<index_lookup>(<cache>(`test`.`t1`.`b`) in t2 on a))))
|
|
DEALLOCATE PREPARE stmt1;
|
|
Test optimizer_switch settings with SUBQUERY hint
|
|
SET optimizer_switch='materialization=off';
|
|
This query will now use In-to-exist
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ min(a) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(/* select#2 */ select /*+ QB_NAME(`subq`) */ 1 from `test`.`t1` group by `test`.`t1`.`a` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(min(`test`.`t1`.`a`)))))
|
|
Force it to use Materialization
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) */ min(a) FROM t1 group by a);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ min(`test`.`t1`.`a`) from `test`.`t1` group by `test`.`t1`.`a` having true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`min(a)`)))))
|
|
SET optimizer_switch='materialization=on,subquery_materialization_cost_based=off';
|
|
This query will now use materialization
|
|
EXPLAIN
|
|
SELECT a, a IN (SELECT a FROM t1) FROM t2;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`))))) AS `a IN (SELECT a FROM t1)` from `test`.`t2`
|
|
Force In-to-exists
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq INTOEXISTS) */ a,
|
|
a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1) FROM t2;
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` INTOEXISTS) */ `test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY))) AS `a IN (SELECT /*+ QB_NAME(subq) */ a FROM t1)` from `test`.`t2`
|
|
Specifying both strategies should give a warning
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 MATERIALIZATION, INTOEXISTS)
|
|
SUBQUERY(@subq2 MATERIALIZATION, INTOEXISTS) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
|
|
1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Warning 1064 Optimizer hint syntax error near ', INTOEXISTS)
|
|
SUBQUERY(@subq2 MATERIALIZATION, INTOEXISTS) */ *
|
|
FROM t3
|
|
WHERE t3' at line 2
|
|
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and (`test`.`tx`.`a` = `test`.`t3`.`a`))
|
|
Non-supported strategies should give warnings
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq1 FIRSTMATCH) SUBQUERY(@subq2 LOOSESCAN) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB_NAME(subq1) */ a FROM t1 tx)
|
|
AND t3.b IN (SELECT /*+ QB_NAME(subq2) */ a FROM t1 ty);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t3 NULL ALL a NULL NULL NULL 3 100.00 Using where
|
|
1 SIMPLE tx NULL eq_ref PRIMARY PRIMARY 4 test.t3.a 1 100.00 Using index
|
|
1 SIMPLE ty NULL eq_ref PRIMARY PRIMARY 4 test.t3.b 1 100.00 Using index
|
|
Warnings:
|
|
Warning 1064 Optimizer hint syntax error near 'FIRSTMATCH) SUBQUERY(@subq2 LOOSESCAN) */ *
|
|
FROM t3
|
|
WHERE t3.a IN (SELECT /*+ QB' at line 2
|
|
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` `tx` join `test`.`t1` `ty` join `test`.`t3` where ((`test`.`ty`.`a` = `test`.`t3`.`b`) and (`test`.`tx`.`a` = `test`.`t3`.`a`))
|
|
SET optimizer_switch= default;
|
|
Specifying two SUBQUERY for same query block gives warning
|
|
First has effect, second is ignored
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ SUBQUERY(MATERIALIZATION) SUBQUERY(INTOEXISTS) */ a
|
|
FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY( INTOEXISTS) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`select#2` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`)))))
|
|
Try opposite order
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ SUBQUERY(INTOEXISTS) SUBQUERY(MATERIALIZATION) */ a
|
|
FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY( MATERIALIZATION) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`select#2` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Specify at different levels, hint inside block has effect
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SUBQUERY(INTOEXISTS) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY(@`subq` MATERIALIZATION) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Specify at different levels, opposite order
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq INTOEXISTS) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SUBQUERY(MATERIALIZATION) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 SUBQUERY t1 NULL index PRIMARY PRIMARY 4 NULL 4 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY(@`subq` INTOEXISTS) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` MATERIALIZATION) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,`test`.`t2`.`a` in ( <materialize> (/* select#2 */ select /*+ QB_NAME(`subq`) */ `test`.`t1`.`a` from `test`.`t1` where true ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on <auto_distinct_key> where ((`test`.`t2`.`a` = `materialized-subquery`.`a`)))))
|
|
Specifying combinations of SUBQUERY and SEMIJOIN/NO_SEMIJOIN
|
|
for same query block gives warning
|
|
First has effect, second is ignored
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ SUBQUERY(INTOEXISTS) SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN( ) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`select#2` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Try opposite order
|
|
EXPLAIN
|
|
SELECT * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ NO_SEMIJOIN() SUBQUERY(MATERIALIZATION) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY( MATERIALIZATION) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`select#2`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
Specify at different levels, hint inside block has effect
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq MATERIALIZATION) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE t2 NULL index a a 4 NULL 4 100.00 Using index
|
|
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.a 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY(@`subq` MATERIALIZATION) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = `test`.`t2`.`a`)
|
|
EXPLAIN
|
|
SELECT /*+ SUBQUERY(@subq INTOEXISTS) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) NO_SEMIJOIN() */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SUBQUERY(@`subq` INTOEXISTS) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ NO_SEMIJOIN(@`subq`) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
EXPLAIN
|
|
SELECT /*+ SEMIJOIN(@subq FIRSTMATCH) */ * FROM t2
|
|
WHERE t2.a IN (SELECT /*+ QB_NAME(subq) SUBQUERY(@subq INTOEXISTS) */ a FROM t1);
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 PRIMARY t2 NULL index NULL a 4 NULL 4 100.00 Using where; Using index
|
|
2 DEPENDENT SUBQUERY t1 NULL unique_subquery PRIMARY PRIMARY 4 func 1 100.00 Using index
|
|
Warnings:
|
|
Warning 3126 Hint SEMIJOIN(@`subq` FIRSTMATCH) is ignored as conflicting/duplicated
|
|
Note 1003 /* select#1 */ select /*+ SUBQUERY(@`subq` INTOEXISTS) */ `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on PRIMARY)))
|
|
drop table t1, t2, t3;
|