database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

MDEV-7487 Semi-join optimization for single-table update/delete statements

Browse Source 
This patch allows to use semi-join optimization at the top level of
single-table update and delete statements.
The problem of supporting such optimization became easy to resolve after
processing a single-table update/delete statement started using JOIN
structure. This allowed to use JOIN::prepare() not only for multi-table
updates/deletes but for single-table ones as well. This was done in the
patch for mdev-28883:
Re-design the upper level of handling UPDATE and DELETE statements.

Note that JOIN::prepare() detects all subqueries that can be considered
as candidates for semi-join optimization. The code added by this patch
looks for such candidates at the top level and if such candidates are found
in the processed single-table update/delete the statement is handled in
the same way as a multi-table update/delete.

    Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2023-01-09 22:39:39 -08:00
parent e2e3524d72
commit 554278e24d
14 changed files with 6198 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
mysql-test/main/myisam_explain_non_select_all.result
View File

@ -218,14 +218,16 @@ INSERT INTO t2 VALUES (1), (2), (3);
#
EXPLAIN UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
2 SUBQUERY t2 ALL NULL NULL NULL NULL 3 Using where
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 SUBQUERY t2 ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1 100.00
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3 100.00 Using where
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_key 4
@ -246,8 +248,9 @@ Handler_read_key 4
Handler_read_rnd_next 5
# Status of testing query execution:
Variable_name Value
Handler_read_key 4
Handler_read_rnd_next 5
Handler_read_key 5
Handler_read_rnd 3
Handler_read_rnd_next 12
Handler_update 3
DROP TABLE t1, t2;
@ -263,13 +266,13 @@ INSERT INTO t2 VALUES (1), (2), (3);
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 3 Using where
1 PRIMARY t2 ALL NULL NULL NULL NULL 3 Using where; FirstMatch(t1)
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY t2 ALL NULL NULL NULL NULL 3 100.00 Using where; FirstMatch(t1)
Warnings:
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
# Status of EXPLAIN EXTENDED query
@ -900,14 +903,16 @@ INSERT INTO t2 VALUES (1), (2), (3), (1000);
#
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 4 Using where
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 4 100.00 Using where
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1 100.00
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3 100.00
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_key 4
@ -928,8 +933,8 @@ Handler_read_key 4
Handler_read_rnd_next 9
# Status of testing query execution:
Variable_name Value
Handler_read_key 4
Handler_read_rnd_next 10
Handler_read_key 7
Handler_read_rnd_next 8
Handler_update 3
DROP TABLE t1, t2;
@ -986,14 +991,14 @@ INSERT INTO t1 VALUES (1), (2), (3), (4), (5);
#
EXPLAIN DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 5 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 5 Using where
1 PRIMARY t1 ALL NULL NULL NULL NULL 5
1 PRIMARY t2 ALL NULL NULL NULL NULL 5 Using where; FirstMatch(t1)
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 5 100.00 Using where
1 PRIMARY t1 ALL NULL NULL NULL NULL 5 100.00
1 PRIMARY t2 ALL NULL NULL NULL NULL 5 100.00 Using where; FirstMatch(t1)
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_key 4
@ -2823,14 +2828,14 @@ INSERT INTO t2 VALUES (1), (2), (3);
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
2 DEPENDENT SUBQUERY <derived3> unique_subquery distinct_key distinct_key 5 func 1
1 PRIMARY <derived3> ref key0 key0 5 test.t1.a 2 FirstMatch(t1)
3 DERIVED t2 ALL NULL NULL NULL NULL 3 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY <derived3> unique_subquery distinct_key distinct_key 5 func 1 100.00
1 PRIMARY <derived3> ref key0 key0 5 test.t1.a 2 100.00 FirstMatch(t1)
3 DERIVED t2 ALL NULL NULL NULL NULL 3 100.00 Using filesort
# Status of EXPLAIN EXTENDED query
Variable_name Value