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Added EQ_REF chaining to the greedy_optimizer
MDEV-28073 Slow query performance in MariaDB when using many table The idea is to prefer and chain EQ_REF tables (tables that uses an unique key to find a row) when searching for the best table combination. This significantly reduces row combinations that has to be examined. This is optimization is enabled when setting optimizer_prune_level=2 (which is now default). Implementation: - optimizer_prune_level has a new level, 2, which enables EQ_REF optimization in addition to the pruning done by level 1. Level 2 is now default. - Added JOIN::eq_ref_tables that contains bits of tables that could use potentially use EQ_REF access in the query. This is calculated in sort_and_filter_keyuse() Under optimizer_prune_level=2: - When the greedy_optimizer notices that the preceding table was an EQ_REF table, it tries to add an EQ_REF table next. If an EQ_REF table exists, only this one will be considered at this level. We also collect all EQ_REF tables chained by the next levels and these are ignored on the starting level as we have already examined these. If no EQ_REF table exists, we continue as normal. This optimization speeds up the greedy_optimizer combination test with ~25% Other things: - I ported the changes in MySQL 5.7 to greedy_optimizer.test to MariaDB to be able to ensure we can handle all cases that MySQL can do. - I have run all tests with --mysqld=--optimizer_prune_level=1 to verify that there where no test changes.
This commit is contained in:
Monty
Oleg Smirnov
@ -1,3 +1,5 @@
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--source include/have_innodb.inc
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#
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# A simple test of the greedy query optimization algorithm and the switches that
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# control the optimizationprocess.
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@ -248,7 +250,7 @@ explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and
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show status like 'Last_query_cost';
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set optimizer_prune_level=1;
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set optimizer_prune_level=2;
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select @@optimizer_prune_level;
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set optimizer_search_depth=0;
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@ -381,6 +383,573 @@ LEFT JOIN (
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SET optimizer_search_depth = DEFAULT;
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DROP TABLE t1,t2,t2_1,t3,t3_1,t4,t4_1,t5,t5_1;
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set join_cache_level=@save_join_cache_level;
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--echo End of 5.0 tests
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set join_cache_level=@save_join_cache_level;
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--echo #
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--echo # Bug #59326: Greedy optimizer produce stupid query execution plans.
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--echo #
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CREATE TABLE t10(
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K INT NOT NULL AUTO_INCREMENT,
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I INT,
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PRIMARY KEY(K)
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);
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INSERT INTO t10(I) VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(0);
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CREATE TABLE t100 LIKE t10;
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INSERT INTO t100(I)
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SELECT X.I FROM t10 AS X,t10 AS Y;
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CREATE TABLE t10000 LIKE t10;
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INSERT INTO t10000(I)
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SELECT X.I FROM t100 AS X, t100 AS Y;
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--disable_warnings
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let $total_handler_reads=
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select sum(variable_value) from information_schema.session_status
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where VARIABLE_NAME like 'Handler_read%';
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--enable_warnings
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## All crossproducts should be executed in order t10,t100,t10000
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EXPLAIN SELECT * FROM t10,t100,t10000;
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EXPLAIN SELECT * FROM t10,t10000,t100;
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EXPLAIN SELECT * FROM t100,t10,t10000;
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EXPLAIN SELECT * FROM t100,t10000,t10;
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EXPLAIN SELECT * FROM t10000,t10,t100;
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EXPLAIN SELECT * FROM t10000,t100,t10;
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######
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## Ordering between T100,T10000 EQ-joined T10 will
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## normally be with smallest EQ-table joined first
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######
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.K=t10.I;
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--source include/expect_qep.inc
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## However, swapping EQ_REF-joined tables gives the same cost
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000,t100
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WHERE t100.K=t10.I
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AND t10000.K=t10.I;
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--source include/check_qep.inc
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#####
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# Expect all variants of EQ joining t100 & t10000 with T10
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# to have same cost # handler_reads:
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.K=t10.I;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.K=t10.I
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AND t10000.K=t10.I;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t100,t10,t10000
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t100,t10000,t10
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10000,t10,t100
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10000,t100,t10
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WHERE t100.K=t10.I
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AND t10000.K=t10.K;
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--source include/check_qep.inc
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#####
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## EQ_REF Should be executed before table scan(ALL)
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## - Independent of #records in table being EQ_REF-joined
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#####
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#####
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# Expect: Join EQ_REF(t100) before ALL(t10000)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/check_qep.inc
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#####
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# Expect: Join EQ_REF(t10000) before ALL(t100) (star-join)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000,t100
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WHERE t100.I=t10.I
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AND t10000.K=t10.I;
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--source include/expect_qep.inc
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--echo # See BUG#18352936
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.I=t10.I
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AND t10000.K=t10.I;
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--source include/check_qep.inc
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--echo # See BUG#18352936
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.I=t10.I
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AND t10000.K=t10.I;
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--source include/check_qep.inc
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#####
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# Expect: Join EQ_REF(t10000) before ALL(t100)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000,t100
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WHERE t100.I=t10.I
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AND t10000.K=t100.I;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.I=t10.I
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AND t10000.K=t100.I;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.I=t10.I
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AND t10000.K=t100.I;
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--source include/check_qep.inc
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#####
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## EQ_REF & ALL join two instances of t10000 with t10:
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## Always EQ_REF join first before producing cross product
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#####
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#####
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before 'cross' ALL(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
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WHERE x.k=t10.i;
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--source include/check_qep.inc
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#####
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before ALL(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/check_qep.inc
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#####
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before ALL(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/check_qep.inc
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## Create indexes to test REF access
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CREATE INDEX IX ON t10(I);
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CREATE INDEX IX ON t100(I);
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CREATE INDEX IX ON t10000(I);
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########
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## EQ_REF Should be executed before 'REF'
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## - Independent of #records in table being EQ_REF-joined
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####
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# Expected QEP: 'join EQ_REF(t100) on t100.K=t10.I' before REF(t10000)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t100,t10000
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000,t100
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WHERE t100.K=t10.I
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AND t10000.I=t10.I;
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--source include/check_qep.inc
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#####
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## EQ_REF & REF join two instances of t10000 with t10:
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#####
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#####
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## Expect this QEP, cost & #handler_read
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before 'cross' ALL(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i;
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--source include/check_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
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WHERE x.k=t10.i;
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--source include/check_qep.inc
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#####
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before REF(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/expect_qep.inc
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/check_qep.inc
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|
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
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WHERE x.k=t10.i
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AND y.i=t10.i;
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--source include/check_qep.inc
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#####
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# Expected QEP: 'join EQ_REF(X) on X.K=t10.I' before REF(Y)
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let $query=
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SELECT STRAIGHT_JOIN COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/expect_qep.inc
|
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|
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let $query=
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SELECT COUNT(*) FROM t10,t10000 x,t10000 y
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/check_qep.inc
|
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|
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let $query=
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SELECT COUNT(*) FROM t10,t10000 y,t10000 x
|
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WHERE x.k=t10.i
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AND y.i=x.k;
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--source include/check_qep.inc
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########
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########
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--echo #
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--echo # Test improved capabilities of analyzing complex query
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--echo # plans without restricting 'optimizer_search_depth'.
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--echo # Fix problems like those reported as bug#41740 & bug#58225.
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--echo #
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--echo # EPLAIN of queries using T1-T62 will timeout/hang wo/ fixes
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--echo #
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DROP TABLE t10, t10000;
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|
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--disable_result_log
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let $tabledef=
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( K INT NOT NULL AUTO_INCREMENT,
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I INT,
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A INT,
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PRIMARY KEY(K), KEY IX(A)
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) engine = InnoDB;
|
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|
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let $analyze = ANALYZE TABLE t100;
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|
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let $i= 1;
|
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while ($i < 62)
|
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{
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let $create= CREATE TABLE t$i $tabledef;
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eval $create;
|
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|
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let $insert =
|
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INSERT INTO t$i(I,A) SELECT X.K,X.K FROM t100 AS X, t100 AS Y WHERE X.K < 20 AND Y.K <= $i;
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eval $insert;
|
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let $analyze = $analyze, t$i;
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inc $i;
|
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}
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eval $analyze;
|
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|
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set optimizer_prune_level=default;
|
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#--enable_result_log
|
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#select @@optimizer_prune_level;
|
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#--disable_result_log
|
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flush status;
|
||||
|
||||
#################
|
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## The EXPLAIN'ed query itself can't be part of the verified
|
||||
## result as the QEP is not 100% predictable due to variation
|
||||
## in statistics from the engines. This is believed to be
|
||||
## caused by:
|
||||
## - Variations in table fill degree.
|
||||
## - 'Fuzzy' statistics provided by engines.
|
||||
## - Round errors caused by 'cost' calculation using
|
||||
## 'only' 64-bit double precision.
|
||||
## - Other bugs...?
|
||||
##
|
||||
###############
|
||||
|
||||
## Will test with optimizer_search_depth= [0,1,3,62]
|
||||
let $depth= 0;
|
||||
while ($depth<4)
|
||||
{
|
||||
if ($depth==0)
|
||||
{
|
||||
set optimizer_search_depth=0;
|
||||
}
|
||||
if ($depth==1)
|
||||
{
|
||||
set optimizer_search_depth=1;
|
||||
}
|
||||
if ($depth==2)
|
||||
{
|
||||
set optimizer_search_depth=3;
|
||||
}
|
||||
if ($depth==3)
|
||||
{
|
||||
set optimizer_search_depth=62;
|
||||
}
|
||||
inc $depth;
|
||||
|
||||
|
||||
## Test pruning of joined table scans (ALL)
|
||||
## Prepare of QEP without timeout is heavily dependent
|
||||
## on maintaining correctly '#rows-sorted' plan
|
||||
##
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i < 61)
|
||||
{
|
||||
let $query= $query JOIN t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
|
||||
select @@optimizer_prune_level;
|
||||
select @@optimizer_search_depth;
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
|
||||
## Test pruning of joined table scans (ALL)
|
||||
## with multiple instances of same table.
|
||||
## (All instances being equally expensive)
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i <= 56)
|
||||
{
|
||||
let $t= t$i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN $t as t$i ON t$i.I=x.I;
|
||||
inc $i;
|
||||
|
||||
select @@optimizer_prune_level;
|
||||
select @@optimizer_search_depth;
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
|
||||
## A mix of 25% EQ_REF / 75% ALL joins
|
||||
##
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i < 60)
|
||||
{
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
|
||||
## A mix of 50% EQ_REF / 50% ALL joins
|
||||
##
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i < 60)
|
||||
{
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
|
||||
## A mix of 75% EQ_REF / 25% ALL joins
|
||||
##
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i < 60)
|
||||
{
|
||||
let $query= $query JOIN t$i ON t$i.I = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
let $query= $query JOIN t$i ON t$i.K = x.I;
|
||||
inc $i;
|
||||
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
|
||||
## 100% EQ_REF joins
|
||||
##
|
||||
let $query= SELECT COUNT(*) FROM t1 AS x;
|
||||
let $i= 1;
|
||||
while ($i < 61)
|
||||
{
|
||||
let $query= $query JOIN t$i ON t$i.K=x.I;
|
||||
inc $i;
|
||||
|
||||
eval EXPLAIN $query;
|
||||
}
|
||||
}
|
||||
|
||||
let $drop = DROP TABLE t100;
|
||||
let $i= 1;
|
||||
while ($i < 62)
|
||||
{
|
||||
let $drop = $drop, t$i;
|
||||
inc $i;
|
||||
}
|
||||
eval $drop;
|
||||
|
||||
--enable_result_log
|
||||
|
||||
show status like "optimizer%";
|
||||
SET OPTIMIZER_SEARCH_DEPTH = DEFAULT;
|
||||
|
||||
--echo #
|
||||
--echo # Bug found when testing greedy optimizer tests
|
||||
--echo #
|
||||
|
||||
CREATE TABLE t1 (pk INTEGER,
|
||||
col_int_key INTEGER,
|
||||
col_varchar_key VARCHAR(8),
|
||||
PRIMARY KEY (pk),
|
||||
KEY (col_varchar_key, col_int_key, pk));
|
||||
|
||||
INSERT INTO t1 values (1,1,"A"),(2,2,"B");
|
||||
explain SELECT * FROM t1 AS alias1
|
||||
WHERE alias1.col_varchar_key IN (SELECT COUNT(*) FROM t1 AS SQ3_alias2 JOIN t1 AS SQ3_alias3 ON (SQ3_alias3.col_varchar_key = SQ3_alias2.col_varchar_key AND SQ3_alias3.pk = SQ3_alias2.pk));
|
||||
drop table t1;
|
||||
|
||||
--echo #
|
||||
--echo # This triggered an assert failure while testing
|
||||
--echo #
|
||||
|
||||
CREATE TABLE t1 (a int, b int, key(b));
|
||||
INSERT INTO t1 VALUES (7,4),(1,1);
|
||||
CREATE TABLE t2 (d int);
|
||||
INSERT INTO t2 VALUES (2),(3);
|
||||
CREATE TABLE t3 (c int);
|
||||
INSERT INTO t3 VALUES (5),(6);
|
||||
SELECT * FROM t1 WHERE 5 IN (SELECT t1_a.a FROM t1 as t1_a WHERE 1 IN (SELECT t1_b.a FROM t1 as t1_b LEFT JOIN (t2 JOIN t3) ON (t1_b.a = t2.d) WHERE t1_b.b < 1));
|
||||
drop table t1,t2,t3;
|
||||
|
||||
--echo End of 10.0 tests
|
||||
|
||||
Reference in New Issue
Block a user