Commit 8fc401e2 authored by gkodinov/kgeorge@magare.gmz's avatar gkodinov/kgeorge@magare.gmz
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Bug #28591: MySQL need not sort the records in case of 

ORDER BY primary_key on InnoDB table

Queries that use an InnoDB secondary index to retrieve
data don't need to sort in case of ORDER BY primary key
if the secondary index is compared to constant(s).
They can also skip sorting if ORDER BY contains both the
the secondary key parts and the primary key parts (in
that order).
This is because InnoDB returns the rows in order of the
primary key for rows with the same values of the secondary
key columns.
Fixed by preventing temp table sort for the qualifying 
queries.
parent 17654758

mysql-test/r/innodb_mysql.result

+245 −0
Original line number Diff line number Diff line
@@ -735,4 +735,249 @@ COUNT(*) 
3072

set @@sort_buffer_size=default;

DROP TABLE t1,t2;

CREATE TABLE t1 (a int, b int, PRIMARY KEY (a), KEY bkey (b)) ENGINE=InnoDB;

INSERT INTO t1 VALUES (1,2),(3,2),(2,2),(4,2),(5,2),(6,2),(7,2),(8,2);

INSERT INTO t1 SELECT a + 8, 2 FROM t1;

INSERT INTO t1 SELECT a + 16, 1 FROM t1;

EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a;

id	1

select_type	SIMPLE

table	t1

type	ref

possible_keys	bkey

key	bkey

key_len	5

ref	const

rows	16

Extra	Using where; Using index

SELECT * FROM t1 WHERE b=2 ORDER BY a;

a	b

1	2

2	2

3	2

4	2

5	2

6	2

7	2

8	2

9	2

10	2

11	2

12	2

13	2

14	2

15	2

16	2

EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;

id	1

select_type	SIMPLE

table	t1

type	range

possible_keys	bkey

key	bkey

key_len	5

ref	NULL

rows	16

Extra	Using where; Using index; Using filesort

SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;

a	b

1	2

2	2

3	2

4	2

5	2

6	2

7	2

8	2

9	2

10	2

11	2

12	2

13	2

14	2

15	2

16	2

17	1

18	1

19	1

20	1

21	1

22	1

23	1

24	1

25	1

26	1

27	1

28	1

29	1

30	1

31	1

32	1

EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;

id	1

select_type	SIMPLE

table	t1

type	range

possible_keys	bkey

key	bkey

key_len	5

ref	NULL

rows	16

Extra	Using where; Using index

SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;

a	b

17	1

18	1

19	1

20	1

21	1

22	1

23	1

24	1

25	1

26	1

27	1

28	1

29	1

30	1

31	1

32	1

1	2

2	2

3	2

4	2

5	2

6	2

7	2

8	2

9	2

10	2

11	2

12	2

13	2

14	2

15	2

16	2

CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a), KEY bkey (b,c))

ENGINE=InnoDB;

INSERT INTO t2 VALUES (1,1,1),(3,1,1),(2,1,1),(4,1,1);

INSERT INTO t2 SELECT a + 4, 1, 1 FROM t2;

INSERT INTO t2 SELECT a + 8, 1, 1 FROM t2;

EXPLAIN SELECT * FROM t2 WHERE b=1 ORDER BY a;

id	1

select_type	SIMPLE

table	t2

type	ref

possible_keys	bkey

key	bkey

key_len	5

ref	const

rows	8

Extra	Using where; Using index; Using filesort

SELECT * FROM t2 WHERE b=1 ORDER BY a;

a	b	c

1	1	1

2	1	1

3	1	1

4	1	1

5	1	1

6	1	1

7	1	1

8	1	1

9	1	1

10	1	1

11	1	1

12	1	1

13	1	1

14	1	1

15	1	1

16	1	1

EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;

id	1

select_type	SIMPLE

table	t2

type	ref

possible_keys	bkey

key	bkey

key_len	10

ref	const,const

rows	8

Extra	Using where; Using index

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;

a	b	c

1	1	1

2	1	1

3	1	1

4	1	1

5	1	1

6	1	1

7	1	1

8	1	1

9	1	1

10	1	1

11	1	1

12	1	1

13	1	1

14	1	1

15	1	1

16	1	1

EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;

id	1

select_type	SIMPLE

table	t2

type	ref

possible_keys	bkey

key	bkey

key_len	10

ref	const,const

rows	8

Extra	Using where; Using index

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;

a	b	c

1	1	1

2	1	1

3	1	1

4	1	1

5	1	1

6	1	1

7	1	1

8	1	1

9	1	1

10	1	1

11	1	1

12	1	1

13	1	1

14	1	1

15	1	1

16	1	1

EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;

id	1

select_type	SIMPLE

table	t2

type	ref

possible_keys	bkey

key	bkey

key_len	10

ref	const,const

rows	8

Extra	Using where; Using index

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;

a	b	c

1	1	1

2	1	1

3	1	1

4	1	1

5	1	1

6	1	1

7	1	1

8	1	1

9	1	1

10	1	1

11	1	1

12	1	1

13	1	1

14	1	1

15	1	1

16	1	1

DROP TABLE t1,t2;

End of 5.0 tests

mysql-test/t/innodb_mysql.test

+33 −0
Original line number Diff line number Diff line
@@ -741,4 +741,37 @@ set @@sort_buffer_size=default; 


DROP TABLE t1,t2;



#

# Bug #28591: MySQL need not sort the records in case of ORDER BY

# primary_key on InnoDB table

#



CREATE TABLE t1 (a int, b int, PRIMARY KEY (a), KEY bkey (b)) ENGINE=InnoDB;

INSERT INTO t1 VALUES (1,2),(3,2),(2,2),(4,2),(5,2),(6,2),(7,2),(8,2);

INSERT INTO t1 SELECT a + 8, 2 FROM t1;

INSERT INTO t1 SELECT a + 16, 1 FROM t1;

query_vertical EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a;

SELECT * FROM t1 WHERE b=2 ORDER BY a;

query_vertical EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;

SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;

query_vertical EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;

SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;



CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a), KEY bkey (b,c))

  ENGINE=InnoDB;

INSERT INTO t2 VALUES (1,1,1),(3,1,1),(2,1,1),(4,1,1);

INSERT INTO t2 SELECT a + 4, 1, 1 FROM t2;

INSERT INTO t2 SELECT a + 8, 1, 1 FROM t2;



query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 ORDER BY a;

SELECT * FROM t2 WHERE b=1 ORDER BY a;

query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;

query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;

query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;

SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;



DROP TABLE t1,t2;



--echo End of 5.0 tests

sql/sql_select.cc

+27 −2
Original line number Diff line number Diff line
@@ -12009,6 +12009,7 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx, 
  key_part_end=key_part+table->key_info[idx].key_parts;

  key_part_map const_key_parts=table->const_key_parts[idx];

  int reverse=0;

  my_bool on_primary_key= FALSE;

  DBUG_ENTER("test_if_order_by_key");



  for (; order ; order=order->next, const_key_parts>>=1)
@@ -12023,7 +12024,30 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx, 
    for (; const_key_parts & 1 ; const_key_parts>>= 1)

      key_part++; 



    if (key_part == key_part_end || key_part->field != field)

    if (key_part == key_part_end)

    {

      /* 

        We are at the end of the key. Check if the engine has the primary

        key as a suffix to the secondary keys. If it has continue to check

        the primary key as a suffix.

      */

      if (!on_primary_key &&

          (table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&

          table->s->primary_key != MAX_KEY)

      {

        on_primary_key= TRUE;

        key_part= table->key_info[table->s->primary_key].key_part;

        key_part_end=key_part+table->key_info[table->s->primary_key].key_parts;

        const_key_parts=table->const_key_parts[table->s->primary_key];



        for (; const_key_parts & 1 ; const_key_parts>>= 1)

          key_part++; 

      }

      else

        DBUG_RETURN(0);

    }



    if (key_part->field != field)

      DBUG_RETURN(0);



    /* set flag to 1 if we can use read-next on key, else to -1 */
@@ -12034,7 +12058,8 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx, 
    reverse=flag;				// Remember if reverse

    key_part++;

  }

  *used_key_parts= (uint) (key_part - table->key_info[idx].key_part);

  *used_key_parts= on_primary_key ? table->key_info[idx].key_parts :

    (uint) (key_part - table->key_info[idx].key_part);

  if (reverse == -1 && !(table->file->index_flags(idx, *used_key_parts-1, 1) &

                         HA_READ_PREV))

    reverse= 0;                                 // Index can't be used

sql/table.cc

+4 −0
Original line number Diff line number Diff line
@@ -780,7 +780,11 @@ int openfrm(THD *thd, const char *name, const char *alias, uint db_stat, 
	      the primary key, then we can use any key to find this column

	    */

	    if (ha_option & HA_PRIMARY_KEY_IN_READ_INDEX)

            {

	      field->part_of_key= share->keys_in_use;

              if (field->part_of_sortkey.is_set(key))

                field->part_of_sortkey= share->keys_in_use;

            }

	  }

	  if (field->key_length() != key_part->length)

	  {