Commit d9b81f3a authored by unknown's avatar unknown
Browse files

EXISTS(SELECT * ...) 

close table before opening in optimize


mysql-test/r/subselect.result:
  test of EXISTS(SELECT * ...)
mysql-test/t/subselect.test:
  test of EXISTS(SELECT * ...)
sql/sql_base.cc:
  EXISTS(SELECT * ...)
sql/sql_table.cc:
  close table before opening one
parent f9ec1ff2

mysql-test/r/subselect.result

+16 −2
Original line number Diff line number Diff line
@@ -328,10 +328,10 @@ patient_uq clinic_uq 
explain extended select * from t6 where exists (select * from t7 where uq = clinic_uq);

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t6	ALL	NULL	NULL	NULL	NULL	4	Using where

2	DEPENDENT SUBQUERY	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.clinic_uq	1	

2	DEPENDENT SUBQUERY	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.clinic_uq	1	Using index

Warnings:

Note	1276	Field or reference 'clinic_uq' of SELECT #2 was resolved in SELECT #1

Note	1003	select test.t6.patient_uq AS `patient_uq`,test.t6.clinic_uq AS `clinic_uq` from test.t6 where exists(select test.t7.uq AS `uq`,test.t7.name AS `name` from test.t7 where (test.t7.uq = test.t6.clinic_uq))

Note	1003	select test.t6.patient_uq AS `patient_uq`,test.t6.clinic_uq AS `clinic_uq` from test.t6 where exists(select 1 AS `Not_used` from test.t7 where (test.t7.uq = test.t6.clinic_uq))

select * from t1 where a= (select a from t2,t4 where t2.b=t4.b);

ERROR 23000: Column: 'a' in field list is ambiguous

drop table t1,t2,t3;
@@ -1817,3 +1817,17 @@ a 
1

3

DROP TABLE t1;

create table t1 (a int, b int);

insert into t1 values (1,2),(3,4);

select * from t1 up where exists (select * from t1 where t1.a=up.a);

a	b

1	2

3	4

explain extended select * from t1 up where exists (select * from t1 where t1.a=up.a);

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	up	ALL	NULL	NULL	NULL	NULL	2	Using where

2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where

Warnings:

Note	1276	Field or reference 'up.a' of SELECT #2 was resolved in SELECT #1

Note	1003	select test.up.a AS `a`,test.up.b AS `b` from test.t1 up where exists(select 1 AS `Not_used` from test.t1 where (test.t1.a = test.up.a))

drop table t1;

mysql-test/t/subselect.test

+9 −0
Original line number Diff line number Diff line
@@ -1158,3 +1158,12 @@ SELECT a FROM t1 WHERE a >= ALL ( SELECT a FROM t1 WHERE b = 2 ); 
SELECT a FROM t1 WHERE a <= ALL ( SELECT a FROM t1 WHERE b = 2 );

SELECT a FROM t1 WHERE a <> ALL ( SELECT a FROM t1 WHERE b = 2 );

DROP TABLE t1;



#

# SELECT(EXISTS * ...)optimisation

#

create table t1 (a int, b int);

insert into t1 values (1,2),(3,4);

select * from t1 up where exists (select * from t1 where t1.a=up.a);

explain extended select * from t1 up where exists (select * from t1 where t1.a=up.a);

drop table t1;

sql/sql_base.cc

+13 −2
Original line number Diff line number Diff line
@@ -2184,7 +2184,18 @@ int setup_wild(THD *thd, TABLE_LIST *tables, List<Item> &fields, 
	!((Item_field*) item)->field)

    {

      uint elem= fields.elements;

      if (insert_fields(thd,tables,((Item_field*) item)->db_name,

      Item_subselect *subsel= thd->lex->current_select->master_unit()->item;

      if (subsel &&

          subsel->substype() == Item_subselect::EXISTS_SUBS)

      {

        /*

          It is EXISTS(SELECT * ...) and we can replace * by any constant.



          Item_int do not need fix_fields() because it is basic constant.

        */

        it.replace(new Item_int("Not_used", (longlong) 1, 21));

      }

      else if (insert_fields(thd,tables,((Item_field*) item)->db_name,

                             ((Item_field*) item)->table_name, &it))

      {

	if (stmt)

sql/sql_table.cc

+1 −0
Original line number Diff line number Diff line
@@ -1861,6 +1861,7 @@ static int mysql_admin_table(THD* thd, TABLE_LIST* tables, 
      TABLE_LIST *save_next= table->next;

      table->next= 0;

      result_code= mysql_recreate_table(thd, table, 0);

      close_thread_tables(thd);

      if (!result_code) // recreation went ok

      {

        if ((table->table= open_ltable(thd, table, lock_type)) &&