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

…ments

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>

mysql-test/main/log_state.result

@@ -243,7 +243,7 @@ rows_examined	sql_text
 4	UPDATE t1 SET a=a+sleep(.02) WHERE a>2
 8	UPDATE t1 SET a=a+sleep(.02) ORDER BY a DESC
 1	UPDATE t2 set b=b+sleep(.02) limit 1
-4	UPDATE t1 SET a=a+sleep(.02) WHERE a in (SELECT b from t2)
+10	UPDATE t1 SET a=a+sleep(.02) WHERE a in (SELECT b from t2)
 6	DELETE FROM t1 WHERE a=a+sleep(.02) ORDER BY a LIMIT 2
 disconnect con2;
 connection default;

mysql-test/main/myisam_explain_non_select_all.result

@@ -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

mysql-test/main/opt_trace.result

@@ -4466,6 +4466,16 @@ explain delete t0,t1 from t0, t1 where t0.a=t1.a and t1.a<3	{
                   }
                 }
               },
+              {
+                "table": "t0",
+                "rowid_filters": [
+                  {
+                    "key": "a",
+                    "build_cost": 0.174715752,
+                    "rows": 3
+                  }
+                ]
+              },
               {
                 "selectivity_for_indexes": [
                   {
@@ -4531,6 +4541,16 @@ explain delete t0,t1 from t0, t1 where t0.a=t1.a and t1.a<3	{
                   }
                 }
               },
+              {
+                "table": "t1",
+                "rowid_filters": [
+                  {
+                    "key": "a",
+                    "build_cost": 0.174715752,
+                    "rows": 3
+                  }
+                ]
+              },
               {
                 "selectivity_for_indexes": [
                   {

mysql-test/main/opt_trace_security.test

@@ -20,9 +20,9 @@ delimiter ;|
 
 --change_user foo
 set optimizer_trace="enabled=on";
-# --error 1142
-# select * from db1.t1;
-# select * from information_schema.OPTIMIZER_TRACE;
+--error 1142
+select * from db1.t1;
+select * from information_schema.OPTIMIZER_TRACE;
 set optimizer_trace="enabled=off";
 
 --change_user root