new IN subquery engine added for simple IN with non-primary index but without NULL returning

(SCRUM) (part of WL#818)

mysql-test/r/subselect.result

@@ -1245,7 +1245,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	func	1	Using where
 2	DEPENDENT SUBQUERY	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using where; Using index
 drop table t1, t2, t3;
-create table t1 (a int, b int, index a (a));
+create table t1 (a int, b int, index a (a,b));
 create table t2 (a int, index a (a));
 create table t3 (a int, b int, index a (a));
 insert into t1 values (1,10), (2,20), (3,30), (4,40);
@@ -1259,7 +1259,15 @@ a
 explain select * from t2 where t2.a in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	ref	a	a	5	func	10	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+a
+2
+4
+explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index; Using where
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 a
 2
@@ -1267,8 +1275,22 @@ a
 explain select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	ref	a	a	5	func	10	Using where
-2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	Using where; Using index
+2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	Using index
+2	DEPENDENT SUBQUERY	t1	ref	a	a	10	func,test.t3.a	100	Using where; Using index
+insert into t1 values (3,31);
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+a
+2
+3
+4
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30 and t1.b <> 31);
+a
+2
+4
+explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index; Using where
 drop table t1, t2, t3;
 create table t1 (a int, b int);
 create table t2 (a int, b int);

mysql-test/t/subselect.test

@@ -824,7 +824,7 @@ explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 explain select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 drop table t1, t2, t3;
-create table t1 (a int, b int, index a (a));
+create table t1 (a int, b int, index a (a,b));
 create table t2 (a int, index a (a));
 create table t3 (a int, b int, index a (a));
 insert into t1 values (1,10), (2,20), (3,30), (4,40);
@@ -841,8 +841,14 @@ insert into t2 values (2), (3), (4), (5);
 insert into t3 values (10,3), (20,4), (30,5);
 select * from t2 where t2.a in (select a from t1);
 explain select * from t2 where t2.a in (select a from t1);
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 explain select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
+insert into t1 values (3,31);
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
+select * from t2 where t2.a in (select a from t1 where t1.b <> 30 and t1.b <> 31);
+explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 drop table t1, t2, t3;
 #
 # alloc_group_fields() working

sql/item_subselect.cc

@@ -972,8 +972,13 @@ int subselect_simplein_engine::exec()
 	((Item_in_subselect *) item)->value= (!cond || cond->val_int()?1:0);
     }
   }
-  {
-    int tmp= 0;
+  DBUG_RETURN(end_exec(table) || (error != 0));
+}
+
+int subselect_simplein_engine::end_exec(TABLE *table)
+{
+  DBUG_ENTER("subselect_simplein_engine::end_exec");
+  int error=0, tmp;
   if ((tmp= table->file->extra(HA_EXTRA_NO_CACHE)))
   {
     DBUG_PRINT("error", ("extra(HA_EXTRA_NO_CACHE) failed"));
@@ -986,8 +991,56 @@ int subselect_simplein_engine::exec()
   }
   if (error == 1)
     table->file->print_error(tmp, MYF(0));
+  DBUG_RETURN(error != 0);
+}
+
+int subselect_indexin_engine::exec()
+{
+  DBUG_ENTER("subselect_indexin_engine::exec");
+  int error;
+  TABLE *table= tab->table;
+  ((Item_in_subselect *) item)->value= 0;
+  if ((tab->ref.key_err= (*tab->ref.key_copy)->copy()))
+  {
+    table->status= STATUS_NOT_FOUND;
+    error= -1;
+  }
+  else
+  {
+    error= table->file->index_read(table->record[0],
+				   tab->ref.key_buff,
+				   tab->ref.key_length,HA_READ_KEY_EXACT);
+    if (error && error != HA_ERR_KEY_NOT_FOUND)
+      error= report_error(table, error);
+    else
+    {
+      for(;;)
+      {
+	error= 0;
+	table->null_row= 0;
+	if (!table->status)
+	{
+	  if (!cond || cond->val_int())
+	  {
+	    ((Item_in_subselect *) item)->value= 1;
+	    goto finish;
+	  }
+	}
+	else
+	  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;
+	}
+      }
+    }
   }
-  DBUG_RETURN(error != 0)
+finish:
+  DBUG_RETURN(end_exec(table) || (error != 0));
 }
 
 uint subselect_single_select_engine::cols()

sql/item_subselect.h

@@ -184,6 +184,7 @@ public:
 
   friend class select_exists_subselect;
   friend class subselect_simplein_engine;
+  friend class subselect_indexin_engine;
 };
 
 /* IN subselect */
@@ -314,6 +315,7 @@ public:
 struct st_join_table;
 class subselect_simplein_engine: public subselect_engine
 {
+protected:
   st_join_table *tab;
   Item *cond;
 public:
@@ -330,4 +332,15 @@ public:
   bool dependent() { return 1; }
   bool uncacheable() { return 1; }
   void  exclude();
+  static int end_exec(TABLE *table);
+};
+
+class subselect_indexin_engine: public subselect_simplein_engine
+{
+public:
+  subselect_indexin_engine(THD *thd, st_join_table *tab_arg,
+			    Item_subselect *subs, Item *where)
+    :subselect_simplein_engine(thd, tab_arg, subs, where)
+  {}
+  int exec();
 };

sql/sql_select.cc

@@ -32,7 +32,7 @@
 
 const char *join_type_str[]={ "UNKNOWN","system","const","eq_ref","ref",
 			      "MAYBE_REF","ALL","range","index","fulltext",
-			      "ref_or_null","simple_in"
+			      "ref_or_null","simple_in","index_in"
 };
 
 static void optimize_keyuse(JOIN *join, DYNAMIC_ARRAY *keyuse_array);
@@ -440,6 +440,42 @@ err:
   DBUG_RETURN(-1);				/* purecov: inspected */
 }
 
+/*
+  test if it is known for optimisation IN subquery
+
+  SYNOPSYS
+    JOIN::test_in_subselect
+    where - pointer for variable in which conditions should be
+            stored if subquery is known
+
+  RETURN
+    1 - known
+    0 - unknown
+*/
+
+bool JOIN::test_in_subselect(Item **where)
+{
+  if (conds->type() == Item::FUNC_ITEM &&
+      ((class Item_func *)this->conds)->functype() == Item_func::EQ_FUNC &&
+      ((Item_func *)conds)->arguments()[0]->type() == Item::REF_ITEM &&
+      ((Item_func *)conds)->arguments()[1]->type() == Item::FIELD_ITEM)
+  {
+    join_tab->info= "Using index";
+    *where= 0;
+    return 1;
+  }
+  if (conds->type() == Item::COND_ITEM &&
+      ((class Item_func *)this->conds)->functype() ==
+      Item_func::COND_AND_FUNC)
+  {
+    *where= conds;
+    join_tab->info= "Using index; Using where";
+    return 1;
+  }
+  return 0;
+}
+
+
 /*
   global select optimisation.
   return 0 - success
@@ -729,30 +765,13 @@ JOIN::optimize()
   */
   if (!group_list && !order && !having &&
       unit->item && unit->item->substype() == Item_subselect::IN_SUBS &&
-      tables == 1 && join_tab[0].type == JT_EQ_REF &&
-      conds &&
+      tables == 1 && conds &&
       !unit->first_select()->next_select())
   {
     Item *where= 0;
-    bool ok= 0;
-    if (conds->type() == Item::FUNC_ITEM &&
-	((class Item_func *)this->conds)->functype() == Item_func::EQ_FUNC &&
-	((Item_func *)conds)->arguments()[0]->type() == Item::REF_ITEM &&
-	((Item_func *)conds)->arguments()[1]->type() == Item::FIELD_ITEM)
+    if (join_tab[0].type == JT_EQ_REF)
     {
-      ok= 1;
-      join_tab->info= "Using index";
-    }
-    else if (conds->type() == Item::COND_ITEM &&
-	     ((class Item_func *)this->conds)->functype() ==
-	     Item_func::COND_AND_FUNC)
-    {
-      ok= 1;
-      where= conds;
-      join_tab->info= "Using index; Using where";
-    }
-
-    if (ok)
+      if (test_in_subselect(&where))
       {
 	join_tab[0].type= JT_SIMPLE_IN;
 	error= 0;
@@ -762,6 +781,19 @@ JOIN::optimize()
 								where)));
       }
     }
+    else if (join_tab[0].type == JT_REF)
+    {
+      if (test_in_subselect(&where))
+      {
+	join_tab[0].type= JT_INDEX_IN;
+	error= 0;
+	DBUG_RETURN(unit->item->
+		    change_engine(new subselect_indexin_engine(thd, join_tab,
+							       unit->item,
+							       where)));
+      }
+    }
+  }
 
   /*
     Need to tell Innobase that to play it safe, it should fetch all

sql/sql_select.h

@@ -76,7 +76,7 @@ typedef struct st_join_cache {
 
 enum join_type { JT_UNKNOWN,JT_SYSTEM,JT_CONST,JT_EQ_REF,JT_REF,JT_MAYBE_REF,
 		 JT_ALL, JT_RANGE, JT_NEXT, JT_FT, JT_REF_OR_NULL,
-		 JT_SIMPLE_IN};
+		 JT_SIMPLE_IN, JT_INDEX_IN};
 
 class JOIN;
 
@@ -277,7 +277,8 @@ class JOIN :public Sql_alloc
   bool rollup_init();
   bool rollup_make_fields(List<Item> &all_fields, List<Item> &fields,
 			  Item_sum ***func);
-  int JOIN::rollup_send_data(uint idx);
+  int rollup_send_data(uint idx);
+  bool test_in_subselect(Item **where);
 };