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c3a7a3c7a2
It was found that unnecessary work of building Ordered_key structures
is being done when processing NULL-aware materialization for IN predicates
having only one column. In fact, the logic for that simplified case can be
expressed as follows.
Say we have predicate left_expr IN (SELECT <subq1>), where left_expr is
scalar(not a tuple).
Then
if (left_expr is NULL) {
if (subq1 produced any rows) {
// note that we don't care if subq1 has produced
// NULLs or not.
NULL IN (<some values>) -> UNKNOWN, i.e. NULL.
} else {
NULL IN ({empty-set}) -> FALSE.
}
} else {
// left_expr is a non-NULL value
if (subq1 output has a match for left_expr) {
left_expr IN (..., left_expr ...) -> TRUE
} else {
// no "known" matches.
if (subq1 output has a NULL) {
left_expr IN ( ... NULL ...) ->
(NULL could have been a match or not)
-> NULL.
} else {
// subq1 didn't produce any "UNKNOWNs" so
// we're positive there weren't any matches
-> FALSE.
}
}
}
This commit introduces subselect_single_column_partial_engine class
implementing the logic described.
Reviewer: Sergei Petrunia <sergey@mariadb.com>
92 lines
3.3 KiB
Text
92 lines
3.3 KiB
Text
set @save_optimizer_switch=@@optimizer_switch;
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create table t1 (a int);
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create table t2 (b int);
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insert into t1 values (null), (1), (2), (3);
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insert into t2 values (3), (4);
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set @@optimizer_switch = "materialization=on,in_to_exists=off,semijoin=off";
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explain format=json select * from t1 where a in (select b from t2);
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--echo # "Complete match" execution strategy
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--source include/analyze-format.inc
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analyze format=json select * from t1 where a in (select b from t2);
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--echo # "Partial match" is used due to NOT IN
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--source include/analyze-format.inc
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analyze format=json select * from t1 where a not in (select b from t2);
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--echo # Subselect in GROUP BY
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--source include/analyze-format.inc
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analyze format=json select a from t1 group by a in (select b from t2);
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--source include/analyze-format.inc
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analyze format=json select a from t1 group by a not in (select b from t2);
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--echo # Subselect in ORDER BY
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--source include/analyze-format.inc
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analyze format=json select a from t1 order by a in (select b from t2);
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--echo # Subselect in HAVING
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--source include/analyze-format.inc
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analyze format=json select a from t1 having a not in (select b from t2);
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--echo # Nested IN
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--source include/analyze-format.inc
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analyze format=json select a from t1 where a in (select a from t1 where a in (select b from t2));
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create table t3 (c int);
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insert into t3 (c) values (3), (null), (4);
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--echo # Subquery in ON-clause of outer join
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--source include/analyze-format.inc
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analyze format=json select a from t1 left join t2 on a not in (select c from t3);
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--source include/analyze-format.inc
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analyze format=json
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select (b, b + 1, b + 2) not in
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(select count(distinct a), a + 1, a + 2 from t1 group by a + 1, a + 2)
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from t2;
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drop table t1, t2, t3;
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--echo #
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--echo # Tables with more than one column
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--echo #
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create table t1 (a1 char(1), a2 char(1));
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insert into t1 values (null, 'b');
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create table t2 (b1 char(1), b2 char(2));
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insert into t2 values ('a','b'), ('c', 'd'), (null, 'e'), ('f', 'g');
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--echo # Force rowid-merge partial matching
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set @@optimizer_switch="partial_match_rowid_merge=on,partial_match_table_scan=off";
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explain format=json select * from t1 where (a1, a2) not in (select b1, b2 from t2);
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--source include/analyze-format.inc
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analyze format=json select * from t1 where (a1, a2) not in (select b1, b2 from t2);
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--echo # Force table scan partial matching
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set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=on";
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--source include/analyze-format.inc
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analyze format=json select * from t1 where (a1, a2) not in (select b1, b2 from t2);
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--echo # Subquery in SELECT list
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explain format=json select t1.*, (a1, a2) in (select * from t2) as in_res from t1;
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--source include/analyze-format.inc
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analyze format=json select t1.*, (a1, a2) in (select * from t2) as in_res from t1;
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--source include/analyze-format.inc
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analyze format=json select t1.*, (a1, a2) not in (select * from t2) as in_res from t1;
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set @@optimizer_switch="partial_match_rowid_merge=on,partial_match_table_scan=off";
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--source include/analyze-format.inc
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analyze format=json select t1.*, (a1, a2) in (select * from t2) as in_res from t1;
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--source include/analyze-format.inc
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analyze format=json select t1.*, (a1, a2) not in (select * from t2) as in_res from t1;
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drop table t1,t2;
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set @@optimizer_switch=@save_optimizer_switch;
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