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).


mysql-test/r/type_bit.result:
  BUG#30324: Grouping queries with COUNT(DISTINCT bit column) return wrong results
  - Testcase
mysql-test/t/type_bit.test:
  BUG#30324: Grouping queries with COUNT(DISTINCT bit column) return wrong results
  - Testcase
sql/item_sum.cc:
  BUG#30324: Grouping queries with COUNT(DISTINCT bit column) return wrong results
  - Make COUNT(DISTINCT ...) code instruct create_tmp_table to create 
    temporary table with BIGINT, not BIT(N) column.

1 files changed, 15 insertions, 0 deletions

diff --git a/mysql-test/r/type_bit.result b/mysql-test/r/type_bit.result
index 5356f7e0712..4c1b80c2fd5 100644
--- a/mysql-test/r/type_bit.result
+++ b/mysql-test/r/type_bit.result
@@ -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