MDEV-22377: Subquery in an [UPDATE] query uses full scan instead of rangebb-10.4-mdev22377

When doing IN->EXISTS rewrite, Item_in_subselect::inject_in_to_exists_cond
injects equalities into subquery's WHERE condition.

The problem is that build_equal_items() has already been called for the
subquery's WHERE, and tampering with the WHERE condition can prevent
equality propagation from working.

If the subquery's WHERE is an Item_cond_and with multiple equalities:
- Item_equal objects form a suffix sub-list of the list in WHERE's
  Item_cond_and::list. The suffix is stored in
  JOIN::cond_equal->current_level.
- Item_cond_and::m_cond_equal must also be preserved.

This patch makes inject_in_to_exists_cond() not to break these properties

1 files changed, 2 insertions, 2 deletions

diff --git a/mysql-test/main/subselect3_jcl6.result b/mysql-test/main/subselect3_jcl6.result
index 4260676cc37..b7b18bf80e0 100644
--- a/mysql-test/main/subselect3_jcl6.result
+++ b/mysql-test/main/subselect3_jcl6.result
@@ -172,7 +172,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 2	DEPENDENT SUBQUERY	t2	ref	a	a	5	test.t1.b	1	100.00	Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
 Warnings:
 Note	1276	Field or reference 'test.t3.oref' of SELECT #2 was resolved in SELECT #1
-Note	1003	/* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<expr_cache><`test`.`t3`.`a`,`test`.`t3`.`oref`>(<in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond(<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null) and `test`.`t2`.`a` = `test`.`t1`.`b` having trigcond(`test`.`t1`.`a` is null)))) AS `Z` from `test`.`t3`
+Note	1003	/* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<expr_cache><`test`.`t3`.`a`,`test`.`t3`.`oref`>(<in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`a` = `test`.`t1`.`b` and `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond(<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null) having trigcond(`test`.`t1`.`a` is null)))) AS `Z` from `test`.`t3`
 drop table t1, t2, t3;
 create table t1 (a int NOT NULL, b int NOT NULL, key(a));
 insert into t1 values 
@@ -200,7 +200,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 2	DEPENDENT SUBQUERY	t2	ref	a	a	4	test.t1.b	1	100.00	Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
 Warnings:
 Note	1276	Field or reference 'test.t3.oref' of SELECT #2 was resolved in SELECT #1
-Note	1003	/* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<expr_cache><`test`.`t3`.`a`,`test`.`t3`.`oref`>(<in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond(<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a`) and `test`.`t2`.`a` = `test`.`t1`.`b`))) AS `Z` from `test`.`t3`
+Note	1003	/* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<expr_cache><`test`.`t3`.`a`,`test`.`t3`.`oref`>(<in_optimizer>(`test`.`t3`.`a`,<exists>(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`a` = `test`.`t1`.`b` and `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond(<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a`)))) AS `Z` from `test`.`t3`
 drop table t1,t2,t3;
 create table t1 (oref int, grp int);
 insert into t1 (oref, grp) values