now we create temporary join for all queries with subqueries to make correct...

now we create temporary join for all queries with subqueries to make correct cleunup of tables and avoid too early unlock (BUG#6841)

mysql-test/t/subselect_innodb.test

@@ -125,3 +125,12 @@ INSERT INTO `t2` VALUES ('yy','xx');
 SELECT R.unit, R.ingredient FROM t1 R WHERE R.ingredient IN (SELECT N.ingredient FROM t2 N WHERE N.unit = R.unit);
 
 drop table t1, t2;
+
+#
+# possible early unlock
+#
+CREATE TABLE t1 ( id INT NOT NULL auto_increment, date1 DATE, coworkerid INT, description VARCHAR(255), sum_used DOUBLE, sum_remaining DOUBLE, comments VARCHAR(255), PRIMARY KEY(id)) engine=innodb;
+insert into t1 values (NULL, '1999-01-01', 1,'test', 22, 33, 'comment'), (NULL, '1999-01-01', 1,'test', 22, 33, 'comment'), (NULL, '1999-01-01', 1,'test', 22, 33, 'comment'), (NULL, '1998-01-01', 1,'test', 22, 33, 'comment'), (NULL, '1998-01-01', 1,'test', 22, 33, 'comment'), (NULL, '2004-01-01', 1,'test', 22, 33, 'comment'), (NULL, '2004-01-01', 1,'test', 22, 33, 'comment');
+SELECT DISTINCT (SELECT sum(sum_used) FROM t1 WHERE sum_used > 0 AND year(date1) <= '2004') as somallontvangsten, (SELECT sum(sum_used) FROM t1 WHERE sum_used < 0 AND year(date1) <= '2004') as somalluitgaven FROM t1;
+select * from t1;
+drop table t1;

sql/sql_lex.cc

@@ -135,7 +135,7 @@ void lex_start(THD *thd, uchar *buf,uint length)
   lex->select_lex.link_prev= (st_select_lex_node**)&(lex->all_selects_list);
   lex->select_lex.options= 0;
   lex->describe= 0;
-  lex->derived_tables= FALSE;
+  lex->subqueries= lex->derived_tables= FALSE;
   lex->lock_option= TL_READ;
   lex->found_colon= 0;
   lex->safe_to_cache_query= 1;

sql/sql_lex.h

@@ -619,6 +619,7 @@ typedef struct st_lex
   bool in_comment, ignore_space, verbose, no_write_to_binlog;
   bool derived_tables;
   bool safe_to_cache_query;
+  bool subqueries;
   ALTER_INFO alter_info;
   /* Prepared statements SQL syntax:*/
   LEX_STRING prepared_stmt_name; /* Statement name (in all queries) */

sql/sql_parse.cc

@@ -3955,6 +3955,7 @@ mysql_new_select(LEX *lex, bool move_down)
   select_lex->init_select();
   if (move_down)
   {
+    lex->subqueries= TRUE;
     /* first select_lex of subselect or derived table */
     SELECT_LEX_UNIT *unit;
     if (!(unit= new(lex->thd->mem_root) SELECT_LEX_UNIT()))

sql/sql_select.cc

@@ -936,7 +936,7 @@ JOIN::optimize()
       }
     }
     
-    if (select_lex->uncacheable)
+    if (thd->lex->subqueries)
     {
       if (!(tmp_join= (JOIN*)thd->alloc(sizeof(JOIN))))
 	DBUG_RETURN(-1);
@@ -3834,6 +3834,7 @@ JOIN::join_free(bool full)
   DBUG_ENTER("JOIN::join_free");
 
   full= full || (!select_lex->uncacheable &&
+                 !thd->lex->subqueries &&
                  !thd->lex->describe); // do not cleanup too early on EXPLAIN
 
   if (table)