MDEV-5582: Plugin 'MEMORY' has ref_count=1 after shutdown with materialization+semijoin

- Let cleanup_empty_jtbm_semi_joins() walk into semi-join nests.

mysql-test/r/subselect_sj2.result

@@ -1112,5 +1112,22 @@ t3 AS t3a INNER JOIN t3 AS t3b ON ( t3a.i3 = t3b.i3 )
 );
 i1
 DROP TABLE t1,t2,t3;
+#
+# MDEV-5582: Plugin 'MEMORY' has ref_count=1 after shutdown with materialization+semijoin
+#
+CREATE TABLE t1 (a INT) engine=innodb;
+INSERT INTO t1 VALUES (8),(9);
+CREATE TABLE t2 (b INT) engine=innodb;
+INSERT INTO t2 VALUES (2),(3);
+CREATE TABLE t3 (c INT, INDEX(c)) engine=innodb;
+INSERT INTO t2 VALUES (4),(5);
+explain
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+3	MATERIALIZED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No matching min/max row
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+a
+DROP TABLE t1,t2,t3;
 # This must be the last in the file:
 set optimizer_switch=@subselect_sj2_tmp;

mysql-test/r/subselect_sj2_jcl6.result

@@ -1127,6 +1127,23 @@ t3 AS t3a INNER JOIN t3 AS t3b ON ( t3a.i3 = t3b.i3 )
 );
 i1
 DROP TABLE t1,t2,t3;
+#
+# MDEV-5582: Plugin 'MEMORY' has ref_count=1 after shutdown with materialization+semijoin
+#
+CREATE TABLE t1 (a INT) engine=innodb;
+INSERT INTO t1 VALUES (8),(9);
+CREATE TABLE t2 (b INT) engine=innodb;
+INSERT INTO t2 VALUES (2),(3);
+CREATE TABLE t3 (c INT, INDEX(c)) engine=innodb;
+INSERT INTO t2 VALUES (4),(5);
+explain
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+3	MATERIALIZED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No matching min/max row
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+a
+DROP TABLE t1,t2,t3;
 # This must be the last in the file:
 set optimizer_switch=@subselect_sj2_tmp;
 #

mysql-test/r/subselect_sj2_mat.result

@@ -1114,6 +1114,23 @@ t3 AS t3a INNER JOIN t3 AS t3b ON ( t3a.i3 = t3b.i3 )
 );
 i1
 DROP TABLE t1,t2,t3;
+#
+# MDEV-5582: Plugin 'MEMORY' has ref_count=1 after shutdown with materialization+semijoin
+#
+CREATE TABLE t1 (a INT) engine=innodb;
+INSERT INTO t1 VALUES (8),(9);
+CREATE TABLE t2 (b INT) engine=innodb;
+INSERT INTO t2 VALUES (2),(3);
+CREATE TABLE t3 (c INT, INDEX(c)) engine=innodb;
+INSERT INTO t2 VALUES (4),(5);
+explain
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+3	MATERIALIZED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No matching min/max row
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+a
+DROP TABLE t1,t2,t3;
 # This must be the last in the file:
 set optimizer_switch=@subselect_sj2_tmp;
 set optimizer_switch=default;

mysql-test/t/subselect_sj2.test

@@ -1249,5 +1249,24 @@ SELECT * FROM t1 WHERE ( 1, 1 ) IN (
 
 DROP TABLE t1,t2,t3;
 
+--echo #
+--echo # MDEV-5582: Plugin 'MEMORY' has ref_count=1 after shutdown with materialization+semijoin
+--echo #
+CREATE TABLE t1 (a INT) engine=innodb;
+INSERT INTO t1 VALUES (8),(9);
+
+CREATE TABLE t2 (b INT) engine=innodb;
+INSERT INTO t2 VALUES (2),(3);
+
+CREATE TABLE t3 (c INT, INDEX(c)) engine=innodb;
+INSERT INTO t2 VALUES (4),(5);
+
+explain
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+SELECT * FROM t1 WHERE 9 IN ( SELECT b FROM t2 WHERE 1 IN ( SELECT MIN(c) FROM t3 ) );
+
+DROP TABLE t1,t2,t3;
+
+
 --echo # This must be the last in the file:
 set optimizer_switch=@subselect_sj2_tmp;

sql/opt_subselect.cc

@@ -5234,9 +5234,9 @@ bool setup_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list,
   through Item::cleanup() calls).
 */
 
-void cleanup_empty_jtbm_semi_joins(JOIN *join)
+void cleanup_empty_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list)
 {
-  List_iterator<TABLE_LIST> li(*join->join_list);
+  List_iterator<TABLE_LIST> li(*join_list);
   TABLE_LIST *table;
   while ((table= li++))
   {
@@ -5248,6 +5248,10 @@ void cleanup_empty_jtbm_semi_joins(JOIN *join)
         table->table= NULL;
       }
     }
+    else if (table->nested_join && table->sj_subq_pred)
+    {
+      cleanup_empty_jtbm_semi_joins(join, &table->nested_join->join_list);
+    }
   }
 }
 

sql/opt_subselect.h

@@ -12,7 +12,7 @@ int pull_out_semijoin_tables(JOIN *join);
 bool optimize_semijoin_nests(JOIN *join, table_map all_table_map);
 bool setup_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list,  
                            Item **join_where);
-void cleanup_empty_jtbm_semi_joins(JOIN *join);
+void cleanup_empty_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list);
 
 // used by Loose_scan_opt
 ulonglong get_bound_sj_equalities(TABLE_LIST *sj_nest, 

sql/sql_select.cc

@@ -10549,7 +10549,7 @@ void JOIN::cleanup(bool full)
   }
   if (full)
   {
-    cleanup_empty_jtbm_semi_joins(this);
+    cleanup_empty_jtbm_semi_joins(this, join_list);
     /* 
       Ensure that the following delete_elements() would not be called
       twice for the same list.