MDEV-25008 [poc] Estimate outer_lookup_keys later in mysql_delete

TODO:
- better estimate? not just row numbers
- UPDATE

mysql-test/main/explain_non_select.result

@@ -289,9 +289,9 @@ insert into t3 values (7), (5), (7), (3);
 explain extended delete from t1 where a in (select pk from t2);
 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	unique_subquery	PRIMARY	PRIMARY	4	func	1	100.00	Using index
+2	MATERIALIZED	t2	index	PRIMARY	PRIMARY	4	NULL	3	100.00	Using index
 Warnings:
-Note	1003	/* select#1 */ delete  from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,<exists>(<primary_index_lookup>(<cache>(`test`.`t1`.`a`) in t2 on PRIMARY)))
+Note	1003	/* select#1 */ delete  from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`pk` from `test`.`t2` ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`pk`)))
 delete from t1 where a in (select pk from t2);
 select * from t1;
 a

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)
+6	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

@@ -251,7 +251,7 @@ Warning	1287	'<select expression> INTO <destination>;' is deprecated and will be
 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	
-2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	3	Using where
+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);
@@ -1027,15 +1027,15 @@ Warning	1287	'<select expression> INTO <destination>;' is deprecated and will be
 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	3	Using where
+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	3	100.00	Using where
+2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	
 Warnings:
-Note	1003	/* select#1 */ update `test`.`t1` set `test`.`t1`.`a` = 10 where <in_optimizer>(`test`.`t1`.`a`,<exists>(/* select#2 */ select `test`.`t2`.`a` from `test`.`t2` where <cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`))
+Note	1003	/* select#1 */ update `test`.`t1` set `test`.`t1`.`a` = 10 where <in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`a` from `test`.`t2` ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`a`)))
 # Status of EXPLAIN EXTENDED query
 Variable_name	Value
 Handler_read_key	4
@@ -1059,8 +1059,8 @@ Handler_read_key	7
 Handler_read_rnd_next	8
 # 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;

mysql-test/main/subselect2.result

@@ -172,7 +172,7 @@ SELECT * FROM t2,t3 WHERE (2,9) IN (SELECT DISTINCT a,pk FROM v1) OR a = b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	a	a	5	NULL	2	Using where; Using index
 1	PRIMARY	t3	ref	b	b	5	test.t2.a	2	Using index
-2	SUBQUERY	t1	const	PRIMARY,a	PRIMARY	4	const	1	Using where
+2	MATERIALIZED	t1	index	PRIMARY,a	a	5	NULL	2	Using index
 SELECT * FROM t2,t3 WHERE (2,9) IN (SELECT DISTINCT a,pk FROM v1) OR a = b;
 pk	a	b
 0	4	4

mysql-test/main/subselect4.result

@@ -2757,8 +2757,16 @@ select 1
 from t2 join t1 on
 ('i','w') not in (select t1.v1,t4.v2 from t4,t1,t3 where t3.v2 = t1.v1) LIMIT ROWS EXAMINED 500;
 1
-Warnings:
-Warning	1931	Query execution was interrupted. The query exceeded LIMIT ROWS EXAMINED 500. The query result may be incomplete
+1
+1
+1
+1
+1
+1
+1
+1
+1
+1
 SET join_cache_level= @save_join_cache_level;
 DROP TABLE t1,t2,t3,t4;
 #
@@ -3101,10 +3109,10 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	test.t2.b	1	100.00	
 2	MATERIALIZED	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
-4	SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+4	MATERIALIZED	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	
 3	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from  <materialize> (/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) join `test`.`t2` where `<subquery2>`.`c` = `test`.`t2`.`b`
+Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from  <materialize> (/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),(/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1) in ( <materialize> (/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` ), <primary_index_lookup>(<cache>(`test`.`t1`.`a`) in <temporary table> on distinct_key where <cache>(`test`.`t1`.`a`) = `<subquery4>`.`d`)))) join `test`.`t2` where `<subquery2>`.`c` = `test`.`t2`.`b`
 select b from t2
 where b in (select c from t3
 group by (select a from t1 where a = 1) in (select d from t4));
@@ -3116,10 +3124,10 @@ group by (select a from t1 where a = 1) in
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
-4	SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+4	MATERIALIZED	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	
 3	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <nop>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) <= <cache>(`test`.`t2`.`b`)))
+Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <nop>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),(/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1) in ( <materialize> (/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` ), <primary_index_lookup>(<cache>(`test`.`t1`.`a`) in <temporary table> on distinct_key where <cache>(`test`.`t1`.`a`) = `<subquery4>`.`d`)))) <= <cache>(`test`.`t2`.`b`)))
 select b from t2
 where b >= any (select c from t3
 group by (select a from t1 where a = 1) in
@@ -3132,10 +3140,10 @@ group by (select a from t1 where a = 1) in
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
-4	SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+4	MATERIALIZED	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	
 3	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <not>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) < <cache>(`test`.`t2`.`b`)))
+Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <not>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),(/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1) in ( <materialize> (/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` ), <primary_index_lookup>(<cache>(`test`.`t1`.`a`) in <temporary table> on distinct_key where <cache>(`test`.`t1`.`a`) = `<subquery4>`.`d`)))) < <cache>(`test`.`t2`.`b`)))
 select b from t2
 where b <= all (select c from t3
 group by (select a from t1 where a = 1) in
@@ -3261,19 +3269,17 @@ EXPLAIN
       "access_type": "ALL",
       "rows": 3,
       "filtered": 100,
-      "attached_condition": "t1.a = <cache>((<in_optimizer>((subquery#2),<exists>(subquery#3))) + 1)"
+      "attached_condition": "t1.a = <cache>((<in_optimizer>((subquery#2),(subquery#2) in (subquery#3))) + 1)"
     },
     "subqueries": [
       {
         "query_block": {
           "select_id": 3,
-          "having_condition": "trigcond(t3.c is null)",
           "table": {
             "table_name": "t3",
             "access_type": "ALL",
             "rows": 2,
-            "filtered": 100,
-            "attached_condition": "trigcond(1 = t3.c or t3.c is null)"
+            "filtered": 100
           }
         }
       },

mysql-test/main/subselect_extra_no_semijoin.result

@@ -353,9 +353,9 @@ WHERE t.a IN (SELECT b FROM t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-3	DEPENDENT SUBQUERY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
+3	MATERIALIZED	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t2` where <expr_cache><0>(<in_optimizer>(0,<exists>(/* select#3 */ select 0 from dual where <cache>(0) = 0)))
+Note	1003	/* select#1 */ select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t2` where <expr_cache><0>(<in_optimizer>(0,0 in ( <materialize> (/* select#3 */ select 0 from dual ), <primary_index_lookup>(0 in <temporary table> on distinct_key where 0 = `<subquery3>`.`b`))))
 SELECT * FROM t2 RIGHT JOIN v1 AS t ON t.a != 0
 WHERE t.a IN (SELECT b FROM t1);
 a	a	b
@@ -366,9 +366,9 @@ WHERE t.a IN (SELECT b FROM t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-2	DEPENDENT SUBQUERY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
+2	MATERIALIZED	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t2` where <expr_cache><0>(<in_optimizer>(0,<exists>(/* select#2 */ select 0 from dual where <cache>(0) = 0)))
+Note	1003	/* select#1 */ select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t2` where <expr_cache><0>(<in_optimizer>(0,0 in ( <materialize> (/* select#2 */ select 0 from dual ), <primary_index_lookup>(0 in <temporary table> on distinct_key where 0 = `<subquery2>`.`b`))))
 DROP VIEW v1;
 DROP TABLE t1,t2;
 #

mysql-test/main/subselect_no_semijoin.result

@@ -4600,7 +4600,7 @@ Note	1003	/* select#1 */ select 1 AS `1` from `test`.`t1` where 1
 EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT min(a) FROM t1 WHERE a > 3 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
-2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using temporary
+2	MATERIALIZED	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using temporary
 Warnings:
 Note	1003	/* select#1 */ select 1 AS `1` from `test`.`t1` where 0
 SET join_cache_level=@save_join_cache_level;

mysql-test/suite/heap/heap.result

@@ -794,7 +794,7 @@ EXPLAIN SELECT col_int_nokey FROM t2
 WHERE ('h', 0) NOT IN ( SELECT * FROM v1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	
-2	SUBQUERY	<derived3>	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	MATERIALIZED	<derived3>	ALL	NULL	NULL	NULL	NULL	2	
 3	DERIVED	t1	range	PRIMARY	PRIMARY	4	NULL	1	Using index condition; Using where
 DROP TABLE t1,t2,h1;
 DROP VIEW v1;

sql/opt_range.cc

@@ -2629,7 +2629,6 @@ static int fill_used_fields_bitmap(PARAM *param)
 
     In the table struct the following information is updated:
       quick_keys           - Which keys can be used
-      quick_rows           - How many rows the key matches
       opt_range_condition_rows - E(# rows that will satisfy the table condition)
 
   IMPLEMENTATION

sql/opt_subselect.cc

@@ -6606,11 +6606,8 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
     }
     else
     {
-      /*
-        TODO: outer_join can be NULL for DELETE statements.
-        How to compute its cost?
-      */
-      outer_lookup_keys= 1;
+      outer_lookup_keys=
+        (double) unit->outer_select()->table_list.first->table->stat_records();
     }
 
     /*

sql/sql_delete.cc

@@ -404,8 +404,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     }
   }
 
-  /* Apply the IN=>EXISTS transformation to all subqueries and optimize them. */
-  if (select_lex->optimize_unflattened_subqueries(false))
+  if (select_lex->optimize_unflattened_subqueries(true))
     DBUG_RETURN(TRUE);
 
   const_cond= (!conds || conds->const_item());
@@ -534,6 +533,9 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     DBUG_RETURN(0);				// Nothing to delete
   }
 
+  if (select_lex->optimize_unflattened_subqueries(false))
+    DBUG_RETURN(TRUE);
+
   /* If running in safe sql mode, don't allow updates without keys */
   if (!select || !select->quick)
   {

sql/sql_update.cc

@@ -535,7 +535,7 @@ int mysql_update(THD *thd,
   switch_to_nullable_trigger_fields(values, table);
 
   /* Apply the IN=>EXISTS transformation to all subqueries and optimize them */
-  if (select_lex->optimize_unflattened_subqueries(false))
+  if (select_lex->optimize_unflattened_subqueries(true))
     DBUG_RETURN(TRUE);
 
   if (select_lex->inner_refs_list.elements &&
@@ -602,6 +602,9 @@ int mysql_update(THD *thd,
     DBUG_RETURN(0);
   }
 
+  if (select_lex->optimize_unflattened_subqueries(false))
+    DBUG_RETURN(TRUE);
+
   /* If running in safe sql mode, don't allow updates without keys */
   if (!select || !select->quick)
   {