Commit 8a3e6201 authored by sergefp@mysql.com's avatar sergefp@mysql.com
Browse files

BUG#30324: Grouping queries with COUNT(DISTINCT bit column) return wrong results 

- The bug was caused by COUNT(DISTINCT ...) code using Unique object in 
  a way that assumed that BIT(N) column occupies a contiguous space in
  temp_table->record[0] buffer. 
- The fix is to make COUNT(DISTINCT ...) code instruct create_tmp_table to
  create temporary table with column of type BIGINT, not BIT(N).
parent 33eaf2cd

mysql-test/r/type_bit.result

+15 −0
Original line number Diff line number Diff line
@@ -657,4 +657,19 @@ b 
#

#

DROP TABLE t1;

CREATE TABLE t1 (a int, b bit(2));

INSERT INTO t1 VALUES (3, 2), (2, 3), (2, 0), (3, 2), (3, 1);

SELECT COUNT(DISTINCT b) FROM t1 GROUP BY a;

COUNT(DISTINCT b)

2

2

DROP TABLE t1;

create table t2 (a int, b bit(2), c char(10));

INSERT INTO t2 VALUES (3, 2, 'two'), (2, 3, 'three'), (2, 0, 'zero'), 

(3, 2, 'two'), (3, 1, 'one');

SELECT COUNT(DISTINCT b,c) FROM t2 GROUP BY a;

COUNT(DISTINCT b,c)

2

2

DROP TABLE t2;

End of 5.0 tests

mysql-test/t/type_bit.test

+14 −0
Original line number Diff line number Diff line
@@ -304,4 +304,18 @@ SELECT b FROM t1 GROUP BY b; 
--disable_metadata

DROP TABLE t1;



#

# BUG#30324 Wrong query result for COUNT(DISTINCT(bit_column))

#

CREATE TABLE t1 (a int, b bit(2));

INSERT INTO t1 VALUES (3, 2), (2, 3), (2, 0), (3, 2), (3, 1);

SELECT COUNT(DISTINCT b) FROM t1 GROUP BY a;

DROP TABLE t1;



create table t2 (a int, b bit(2), c char(10));

INSERT INTO t2 VALUES (3, 2, 'two'), (2, 3, 'three'), (2, 0, 'zero'), 

                      (3, 2, 'two'), (3, 1, 'one');

SELECT COUNT(DISTINCT b,c) FROM t2 GROUP BY a;

DROP TABLE t2;



--echo End of 5.0 tests

sql/item_sum.cc

+17 −0
Original line number Diff line number Diff line
@@ -2464,6 +2464,23 @@ bool Item_sum_count_distinct::setup(THD *thd) 
  count_field_types(select_lex, tmp_table_param, list, 0);

  tmp_table_param->force_copy_fields= force_copy_fields;

  DBUG_ASSERT(table == 0);

  /*

    Make create_tmp_table() convert BIT columns to BIGINT.

    This is needed because BIT fields store parts of their data in table's

    null bits, and we don't have methods to compare two table records, which

    is needed by Unique which is used when HEAP table is used.

  */

  {

    List_iterator_fast<Item> li(list);

    Item *item;

    while ((item= li++))

    {

      if (item->type() == Item::FIELD_ITEM &&

          ((Item_field*)item)->field->type() == FIELD_TYPE_BIT)

        item->marker=4;

    }

  }



  if (!(table= create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,

				0,

				(select_lex->options | thd->options),