Fixed a problem where the temp table of a materialized subquery

was not cleaned up between PS re-executions. The reason was two-fold:
- a merge with mysql-6.0 missed select_union::cleanup() that should
  have cleaned up the temp table, and
- the subclass of select_union used by materialization didn't call
  the base class cleanup() method.

mysql-test/r/subselect_mat.result

@@ -1246,3 +1246,29 @@ i
 4
 set session optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
+create table t0 (a int);
+insert into t0 values (0),(1),(2);
+create table t1 (a int);
+insert into t1 values (0),(1),(2);
+explain select a, a in (select a from t1) from t0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	3	
+2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
+select a, a in (select a from t1) from t0;
+a	a in (select a from t1)
+0	1
+1	1
+2	1
+prepare s from 'select a, a in (select a from t1) from t0';
+execute s;
+a	a in (select a from t1)
+0	1
+1	1
+2	1
+update t1 set a=123;
+execute s;
+a	a in (select a from t1)
+0	0
+1	0
+2	0
+drop table t0, t1;

mysql-test/t/subselect_mat.test

@@ -905,3 +905,19 @@ select * from t1 where t1.i in (select t2.i from t2 join t3 where t2.i + t3.i =
 set session optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 
+#
+# Test that the contents of the temp table of a materialized subquery is
+# cleaned up between PS re-executions.
+#
+
+create table t0 (a int);
+insert into t0 values (0),(1),(2);
+create table t1 (a int);
+insert into t1 values (0),(1),(2);
+explain select a, a in (select a from t1) from t0;
+select a, a in (select a from t1) from t0;
+prepare s from 'select a, a in (select a from t1) from t0';
+execute s;
+update t1 set a=123;
+execute s;
+drop table t0, t1;

sql/sql_class.cc

@@ -2994,14 +2994,28 @@ create_result_table(THD *thd_arg, List<Item> *column_types,
   if (!stat)
     return TRUE;
 
-  cleanup();
-
+  reset();
   table->file->extra(HA_EXTRA_WRITE_CACHE);
   table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
   return FALSE;
 }
 
 
+void select_materialize_with_stats::reset()
+{
+  memset(col_stat, 0, table->s->fields * sizeof(Column_statistics));
+  max_nulls_in_row= 0;
+  count_rows= 0;
+}
+
+
+void select_materialize_with_stats::cleanup()
+{
+  reset();
+  select_union::cleanup();
+}
+
+
 /**
   Override select_union::send_data to analyze each row for NULLs and to
   update null_statistics before sending data to the client.

sql/sql_class.h

@@ -2905,7 +2905,7 @@ public:
   bool send_data(List<Item> &items);
   bool send_eof();
   bool flush();
-
+  void cleanup();
   virtual bool create_result_table(THD *thd, List<Item> *column_types,
                                    bool is_distinct, ulonglong options,
                                    const char *alias, bool bit_fields_as_long);
@@ -2968,6 +2968,9 @@ protected:
   */
   ha_rows count_rows;
 
+protected:
+  void reset();
+
 public:
   select_materialize_with_stats() {}
   virtual bool create_result_table(THD *thd, List<Item> *column_types,
@@ -2975,12 +2978,7 @@ public:
                                    const char *alias, bool bit_fields_as_long);
   bool init_result_table(ulonglong select_options);
   bool send_data(List<Item> &items);
-  void cleanup()
-  {
-    memset(col_stat, 0, table->s->fields * sizeof(Column_statistics));
-    max_nulls_in_row= 0;
-    count_rows= 0;
-  }
+  void cleanup();
   ha_rows get_null_count_of_col(uint idx)
   {
     DBUG_ASSERT(idx < table->s->fields);

sql/sql_union.cc

@@ -136,6 +136,22 @@ select_union::create_result_table(THD *thd_arg, List<Item> *column_types,
 }
 
 
+/**
+  Reset and empty the temporary table that stores the materialized query result.
+
+  @note The cleanup performed here is exactly the same as for the two temp
+  tables of JOIN - exec_tmp_table_[1 | 2].
+*/
+
+void select_union::cleanup()
+{
+  table->file->extra(HA_EXTRA_RESET_STATE);
+  table->file->ha_delete_all_rows();
+  free_io_cache(table);
+  filesort_free_buffers(table,0);
+}
+
+
 /*
   initialization procedures before fake_select_lex preparation()