MDEV-16088: Pushdown into materialized views/derived tables doesn't

            work in the IN subqueries

The pushdown into the materialized derived table/view wasn't done because
optimize() for the derived was called before any conditions that can
be pushed down were extracted. So optimize() in
convert_join_subqueries_to_semijoins() method is called too early and is
unnecessary. The second optimize() call in mysql_handle_single_derived()
is enough.

mysql-test/r/derived_view.result

@@ -1841,7 +1841,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	Using where
 1	PRIMARY	<derived3>	ALL	NULL	NULL	NULL	NULL	3	Using where; Start temporary; End temporary
-3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT * FROM t3 
 WHERE t3.b IN (SELECT v1.b FROM  v1, t2 
 WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);
@@ -1856,7 +1856,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	
 1	PRIMARY	<derived3>	ref	key1	key1	8	const,const	0	Start temporary
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	Using where; End temporary; Using join buffer (flat, BNL join)
-3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT * FROM t3 
 WHERE t3.b IN (SELECT v1.b FROM  v1, t2 
 WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);

mysql-test/r/subselect_extra.result

@@ -434,7 +434,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	Using where
 1	PRIMARY	<derived3>	ALL	NULL	NULL	NULL	NULL	3	Using where; FirstMatch(t3); Using join buffer (flat, BNL join)
-3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT * FROM t3 
 WHERE t3.b IN (SELECT v1.b FROM  v1, t2 
 WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);
@@ -449,7 +449,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	
 1	PRIMARY	<derived3>	ref	key1	key1	8	const,const	0	Start temporary
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	Using where; End temporary; Using join buffer (flat, BNL join)
-3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT * FROM t3 
 WHERE t3.b IN (SELECT v1.b FROM  v1, t2 
 WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);

mysql-test/t/derived_cond_pushdown.test

@@ -1646,3 +1646,86 @@ select * from (select  date('2018-01-01') as d
 
 select * from (select  date('2018-01-01') as d) as t
   where t.d between date ('2017-01-01') and date ('2019-01-01');
+
+--echo #
+--echo # MDEV-16088: pushdown into derived defined in the IN subquery
+--echo #
+
+CREATE TABLE t1 (a INT, b INT);
+CREATE TABLE t2 (e INT, f INT, g INT);
+INSERT INTO t1 VALUES (1,14),(2,13),(1,19),(2,32),(3,24);
+INSERT INTO t2 VALUES (1,19,2),(3,24,1),(1,12,2),(3,11,3),(2,32,1);
+
+LET $query=
+SELECT * FROM t1
+WHERE (t1.a,t1.b) IN
+  (
+    SELECT d_tab.e,d_tab.max_f
+    FROM (
+      SELECT t2.e, MAX(t2.f) AS max_f
+      FROM t2
+      GROUP BY t2.e
+      HAVING max_f>18
+    ) as d_tab
+    WHERE d_tab.e>1
+  )
+;
+EVAL $query;
+EVAL EXPLAIN $query;
+EVAL EXPLAIN FORMAT=JSON $query;
+
+LET $query=
+SELECT * FROM t1
+WHERE (t1.a,t1.b) IN
+  (
+    SELECT d_tab.e,d_tab.max_f
+    FROM (
+      SELECT t2.e, MAX(t2.f) AS max_f
+      FROM t2
+      GROUP BY t2.e
+      HAVING max_f>18
+    ) as d_tab
+    WHERE d_tab.max_f<25
+  )
+;
+EVAL $query;
+EVAL EXPLAIN $query;
+EVAL EXPLAIN FORMAT=JSON $query;
+
+LET $query=
+SELECT * FROM t1
+WHERE (t1.a,t1.b) IN
+  (
+    SELECT d_tab.e, MAX(d_tab.max_f) AS max_f
+    FROM (
+      SELECT t2.e, MAX(t2.f) as max_f, t2.g
+      FROM t2
+      GROUP BY t2.e
+    ) as d_tab
+    WHERE d_tab.e>1
+    GROUP BY d_tab.g
+  )
+;
+EVAL $query;
+EVAL EXPLAIN $query;
+EVAL EXPLAIN FORMAT=JSON $query;
+
+LET $query=
+SELECT * FROM t1
+WHERE (t1.a,t1.b) IN
+  (
+    SELECT d_tab.e, MAX(d_tab.max_f) AS max_f
+    FROM (
+      SELECT t2.e, MAX(t2.f) as max_f, t2.g
+      FROM t2
+      GROUP BY t2.e
+    ) as d_tab
+    WHERE d_tab.max_f>20
+    GROUP BY d_tab.g
+  )
+;
+EVAL $query;
+EVAL EXPLAIN $query;
+EVAL EXPLAIN FORMAT=JSON $query;
+
+DROP TABLE t1,t2;

sql/opt_subselect.cc

@@ -1092,8 +1092,6 @@ bool convert_join_subqueries_to_semijoins(JOIN *join)
   while ((in_subq= li++))
   {
     SELECT_LEX *subq_sel= in_subq->get_select_lex();
-    if (subq_sel->handle_derived(thd->lex, DT_OPTIMIZE))
-      DBUG_RETURN(1);
     if (subq_sel->handle_derived(thd->lex, DT_MERGE))
       DBUG_RETURN(TRUE);
     subq_sel->update_used_tables();