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

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- 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).
This commit is contained in:
sergefp@mysql.com 2007-09-14 14:53:13 +04:00
parent 33eaf2cd95
commit 8a3e6201b3
3 changed files with 46 additions and 0 deletions
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15
mysql-test/r/type_bit.result
View file

@ -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

14
mysql-test/t/type_bit.test
View file

@ -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

17
sql/item_sum.cc
View file

@ -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),