From 466747d57081b4bdfe166ff16da8ac9da99900e4 Mon Sep 17 00:00:00 2001
From: unknown <sergefp@mysql.com>
Date: Fri, 14 Sep 2007 14:53:13 +0400
Subject: [PATCH] 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.
---
 mysql-test/r/type_bit.result | 15 +++++++++++++++
 mysql-test/t/type_bit.test   | 14 ++++++++++++++
 sql/item_sum.cc              | 17 +++++++++++++++++
 3 files changed, 46 insertions(+)

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
diff --git a/mysql-test/t/type_bit.test b/mysql-test/t/type_bit.test
index 66538f59c6f..4978f55d776 100644
--- a/mysql-test/t/type_bit.test
+++ b/mysql-test/t/type_bit.test
@@ -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
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index fe9f58d84e1..c20d3fba705 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -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),