Commit 5c0cdea6 authored by unknown's avatar unknown
Browse files

BUG#20357 - Got error 124 from storage engine using MIN and MAX 

            functions in queries

Using MAX()/MIN() on table with disabled indexes (by ALTER TABLE)
results in error 124 (wrong index) from storage engine.

The problem was that optimizer use disabled index to optimize
MAX()/MIN(). Normally it must skip disabled index and perform
table scan.

This patch skips disabled indexes for min/max optimization.


mysql-test/r/myisam.result:
  Test case for BUG#20357.
mysql-test/t/myisam.test:
  Test case for BUG#20357.
sql/opt_sum.cc:
  Skip disabled/ignored indexes for min/max optimization.
parent ef02d496

mysql-test/r/myisam.result

+13 −0
Original line number Diff line number Diff line
@@ -748,3 +748,16 @@ select count(id1) from t1 where id2 = 10; 
count(id1)

5

drop table t1;

CREATE TABLE t1(a TINYINT, KEY(a)) ENGINE=MyISAM;

INSERT INTO t1 VALUES(1);

SELECT MAX(a) FROM t1 IGNORE INDEX(a);

MAX(a)

1

ALTER TABLE t1 DISABLE KEYS;

SELECT MAX(a) FROM t1;

MAX(a)

1

SELECT MAX(a) FROM t1 IGNORE INDEX(a);

MAX(a)

1

DROP TABLE t1;

mysql-test/t/myisam.test

+12 −0
Original line number Diff line number Diff line
@@ -705,4 +705,16 @@ select count(*) from t1 where id2 = 10; 
select count(id1) from t1 where id2 = 10;

drop table t1;



#

# BUG##20357 - Got error 124 from storage engine using MIN and MAX functions

#              in queries

#

CREATE TABLE t1(a TINYINT, KEY(a)) ENGINE=MyISAM;

INSERT INTO t1 VALUES(1);

SELECT MAX(a) FROM t1 IGNORE INDEX(a);

ALTER TABLE t1 DISABLE KEYS;

SELECT MAX(a) FROM t1;

SELECT MAX(a) FROM t1 IGNORE INDEX(a);

DROP TABLE t1;



# End of 4.1 tests

sql/opt_sum.cc

+6 −0
Original line number Diff line number Diff line
@@ -673,6 +673,12 @@ static bool find_key_for_maxmin(bool max_fl, TABLE_REF *ref, 
  {

    KEY_PART_INFO *part,*part_end;

    key_part_map key_part_to_use= 0;

    /*

      Perform a check if index is not disabled by ALTER TABLE

      or IGNORE INDEX.

    */

    if (!table->keys_in_use_for_query.is_set(idx))

      continue;

    uint jdx= 0;

    *prefix_len= 0;

    for (part= keyinfo->key_part, part_end= part+keyinfo->key_parts ;