removing additional IN subquery condition

fixed IN optimisation bug

mysql-test/r/subselect.result

@@ -829,7 +829,7 @@ a	t1.a in (select t2.a from t2)
 explain SELECT t1.a, t1.a in (select t2.a from t2) FROM t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	4	Using index
-2	DEPENDENT SUBQUERY	t2	index_in	a	a	5	func	2	Using where; Using index
+2	DEPENDENT SUBQUERY	t2	index_in	a	a	5	func	2	Using index
 CREATE TABLE t3 (a int(11) default '0');
 INSERT INTO t3 VALUES (1),(2),(3);
 SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
@@ -1369,3 +1369,26 @@ select * from t1 where ('a','b')=(select 'a','b' from t1 union select 'a','b' fr
 s1
 tttt
 drop table t1;
+create table t1 (s1 char(5), index s1(s1));
+create table t2 (s1 char(5), index s1(s1));
+insert into t1 values ('a1'),('a2'),('a3');
+insert into t2 values ('a1'),('a2');
+select s1, s1 NOT IN (SELECT s1 FROM t2) from t1;
+s1	s1 NOT IN (SELECT s1 FROM t2)
+a1	0
+a2	0
+a3	1
+select s1, s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2') from t1;
+s1	s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2')
+a1	0
+a2	1
+a3	1
+explain select s1, s1 NOT IN (SELECT s1 FROM t2) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	index	NULL	s1	6	NULL	3	Using index
+2	DEPENDENT SUBQUERY	t2	index_in	s1	s1	6	func	2	Using index
+explain select s1, s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2') from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	index	NULL	s1	6	NULL	3	Using index
+2	DEPENDENT SUBQUERY	t2	index_in	s1	s1	6	func	1	Using index; Using where
+drop table t1,t2;

mysql-test/t/subselect.test

@@ -932,3 +932,16 @@ select (select 'a','b' from t1 union select 'a','b' from t1) from t1;
 insert into t1 values ('tttt');
 select * from t1 where ('a','b')=(select 'a','b' from t1 union select 'a','b' from t1);
 drop table t1;
+
+#
+# IN optimisation test results
+#
+create table t1 (s1 char(5), index s1(s1));
+create table t2 (s1 char(5), index s1(s1));
+insert into t1 values ('a1'),('a2'),('a3');
+insert into t2 values ('a1'),('a2');
+select s1, s1 NOT IN (SELECT s1 FROM t2) from t1;
+select s1, s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2') from t1;
+explain select s1, s1 NOT IN (SELECT s1 FROM t2) from t1;
+explain select s1, s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2') from t1;
+drop table t1,t2;

sql/item_subselect.cc

@@ -576,6 +576,7 @@ Item_in_subselect::single_value_transformer(JOIN *join,
 	item= new Item_cond_or(item,
 			       new Item_func_isnull(isnull));
       }
+      item->name= (char *)in_additional_cond;
       join->conds= and_items(join->conds, item);
       if (join->conds->fix_fields(thd, join->tables_list, &join->conds))
 	DBUG_RETURN(RES_ERROR);
@@ -971,6 +972,7 @@ int subselect_indexin_engine::exec()
 {
   DBUG_ENTER("subselect_indexin_engine::exec");
   int error;
+  bool null_finding= 0;
   TABLE *table= tab->table;
 
   ((Item_in_subselect *) item)->value= 0;
@@ -1002,29 +1004,30 @@ int subselect_indexin_engine::exec()
 	{
 	  if (!cond || cond->val_int())
 	  {
-	    if (check_null && *tab->null_ref_key)
+	    if (null_finding)
 	      ((Item_in_subselect *) item)->was_null= 1;
 	    else
 	      ((Item_in_subselect *) item)->value= 1;
 	    goto finish;
 	  }
+	  error= table->file->index_next_same(table->record[0],
+					      tab->ref.key_buff,
+					      tab->ref.key_length);
+	  if (error && error != HA_ERR_END_OF_FILE)
+	  {
+	    error= report_error(table, error);
+	    goto finish;
+	  }
 	}
 	else
 	{
-	  if (!check_null || *tab->null_ref_key)
+	  if (!check_null || null_finding)
 	    goto finish;
 	  *tab->null_ref_key= 1;
+	  null_finding= 1;
 	  if (safe_index_read(tab))
 	    goto finish;
 	}
-	error= table->file->index_next_same(table->record[0],
-					    tab->ref.key_buff,
-					    tab->ref.key_length);
-	if (error && error != HA_ERR_KEY_NOT_FOUND)
-	{
-	  error= report_error(table, error);
-	  goto finish;
-	}
       }
     }
   }

sql/mysql_priv.h

@@ -716,7 +716,7 @@ extern const char *command_name[];
 extern const char *first_keyword, *localhost, *delayed_user, *binary_keyword;
 extern const char **errmesg;			/* Error messages */
 extern const char *myisam_recover_options_str;
-extern const char *in_left_expr_name;
+extern const char *in_left_expr_name, *in_additional_cond;
 extern uchar *days_in_month;
 extern char language[LIBLEN],reg_ext[FN_EXTLEN];
 extern char glob_hostname[FN_REFLEN], mysql_home[FN_REFLEN];

sql/mysqld.cc

@@ -320,6 +320,8 @@ const char *myisam_recover_options_str="OFF";
 const char *sql_mode_str="OFF";
 /* name of reference on left espression in rewritten IN subquery */
 const char *in_left_expr_name= "<left expr>";
+/* name of additional condition */
+const char *in_additional_cond= "<IN COND>";
 
 FILE *bootstrap_file;
 

sql/sql_select.cc

@@ -160,6 +160,7 @@ static bool init_sum_functions(Item_sum **func, Item_sum **end);
 static bool update_sum_func(Item_sum **func);
 static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
 			    bool distinct, const char *message=NullS);
+static Item *remove_additional_cond(Item* conds);
 
 
 /*
@@ -464,8 +465,10 @@ bool JOIN::test_in_subselect(Item **where)
       ((class Item_func *)this->conds)->functype() ==
       Item_func::COND_AND_FUNC)
   {
-    *where= conds;
-    join_tab->info= "Using index; Using where";
+    if ((*where= remove_additional_cond(conds)))
+      join_tab->info= "Using index; Using where";
+    else
+      join_tab->info= "Using index";
     return 1;
   }
   return 0;
@@ -806,6 +809,12 @@ JOIN::optimize()
     {
       join_tab[0].type= JT_INDEX_IN;
       error= 0;
+
+      if ((conds= remove_additional_cond(conds)))
+	join_tab->info= "Using index; Using where";
+      else
+	join_tab->info= "Using index";
+ 
       DBUG_RETURN(unit->item->
 		  change_engine(new subselect_indexin_engine(thd,
 							     join_tab,
@@ -3990,6 +3999,39 @@ change_cond_ref_to_const(I_List<COND_CMP> *save_list,Item *and_father,
   }
 }
 
+/*
+  Remove additional condition inserted by IN/ALL/ANY transformation
+
+  SYNOPSIS
+    remove_additional_cond()
+    conds - condition for processing
+
+  RETURN VALUES
+    new conditions
+*/
+
+static Item *remove_additional_cond(Item* conds)
+{
+  if (conds->name == in_additional_cond)
+    return 0;
+  if (conds->type() == Item::COND_ITEM)
+  {
+    Item_cond *cnd= (Item_cond*) conds;
+    List_iterator<Item> li(*(cnd->argument_list()));
+    Item *item;
+    while ((item= li++))
+    {
+      if (item->name == in_additional_cond)
+      {
+	li.remove();
+	if (cnd->argument_list()->elements == 1)
+	  return cnd->argument_list()->head();
+	return conds;
+      }
+    }
+  }
+  return conds;
+}
 
 static void
 propagate_cond_constants(I_List<COND_CMP> *save_list,COND *and_level,