#At file:///work/bzr_trees/38195-bug-5.0-opt/
2611 Evgeny Potemkin 2008-08-06
Bug#38195: Incorrect handling of aggregate functions when loose index scan is
used causes server crash.
When the loose index scan access method is used values of aggregated functions
are precomputed by it. Aggregation of such functions shouldn't be performed
in this case and functions should be treated as normal ones.
The create_tmp_table function wasn't taking this into account and this led to
a crash.
Now the JOIN::exec and the create_tmp_table functions treat aggregate
functions as normal ones when the loose index scan is used.
modified:
mysql-test/r/group_min_max.result
mysql-test/t/group_min_max.test
sql/sql_select.cc
per-file messages:
mysql-test/r/group_min_max.result
Added a test case for the bug#38195.
mysql-test/t/group_min_max.test
Added a test case for the bug#38195.
sql/sql_select.cc
Bug#38195: Incorrect handling of aggregate functions when loose index scan is
used causes server crash.
The JOIN::exec and the create_tmp_table functions treat aggregate
functions as normal ones when the loose index scan is used.
=== modified file 'mysql-test/r/group_min_max.result'
--- a/mysql-test/r/group_min_max.result 2007-11-20 14:07:24 +0000
+++ b/mysql-test/r/group_min_max.result 2008-08-06 14:15:55 +0000
@@ -2353,3 +2353,44 @@ a MIN(b) MAX(b) AVG(b)
2 1 3 2.0000
1 1 3 2.0000
DROP TABLE t1;
+create table t1 (a int, b int, primary key (a,b), key `index` (a,b)) engine=MyISAM;
+insert into t1 (a,b) values (0,0),(0,1),(0,2),(0,3),(0,4),(0,5),(0,6),(0,7),
+(0,8),(0,9),(0,10),(0,11),(0,12),(0,13);
+insert into t1 (a,b) select a, max(b)+1 from t1 where a = 0 group by a;
+select * from t1;
+a b
+0 0
+0 1
+0 2
+0 3
+0 4
+0 5
+0 6
+0 7
+0 8
+0 9
+0 10
+0 11
+0 12
+0 13
+0 14
+insert into t1 (a,b) select a, max(b+1)+1 from t1 where a = 0 group by a;
+select * from t1;
+a b
+0 0
+0 1
+0 2
+0 3
+0 4
+0 5
+0 6
+0 7
+0 8
+0 9
+0 10
+0 11
+0 12
+0 13
+0 14
+0 16
+drop table t1;
=== modified file 'mysql-test/t/group_min_max.test'
--- a/mysql-test/t/group_min_max.test 2007-11-20 14:07:24 +0000
+++ b/mysql-test/t/group_min_max.test 2008-08-06 14:15:55 +0000
@@ -916,3 +916,16 @@ SELECT a, MIN(b), MAX(b), AVG(b) FROM t1
SELECT a, MIN(b), MAX(b), AVG(b) FROM t1 GROUP BY a ORDER BY a DESC;
DROP TABLE t1;
+
+#
+# Bug#38195: Incorrect handling of aggregate functions when loose index scan is
+# used causes server crash.
+#
+create table t1 (a int, b int, primary key (a,b), key `index` (a,b)) engine=MyISAM;
+insert into t1 (a,b) values (0,0),(0,1),(0,2),(0,3),(0,4),(0,5),(0,6),(0,7),
+(0,8),(0,9),(0,10),(0,11),(0,12),(0,13);
+insert into t1 (a,b) select a, max(b)+1 from t1 where a = 0 group by a;
+select * from t1;
+insert into t1 (a,b) select a, max(b+1)+1 from t1 where a = 0 group by a;
+select * from t1;
+drop table t1;
=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc 2008-07-26 20:44:07 +0000
+++ b/sql/sql_select.cc 2008-08-06 14:15:55 +0000
@@ -1724,7 +1724,8 @@ JOIN::exec()
if (!items1)
{
items1= items0 + all_fields.elements;
- if (sort_and_group || curr_tmp_table->group)
+ if (sort_and_group || curr_tmp_table->group ||
+ tmp_table_param.precomputed_group_by)
{
if (change_to_use_tmp_fields(thd, items1,
tmp_fields_list1, tmp_all_fields1,
@@ -9259,6 +9260,8 @@ create_tmp_table(THD *thd,TMP_TABLE_PARA
MI_COLUMNDEF *recinfo;
uint total_uneven_bit_length= 0;
bool force_copy_fields= param->force_copy_fields;
+ /* Treat sum functions as normal ones when loose index scan is used. */
+ save_sum_fields|= param->precomputed_group_by;
DBUG_ENTER("create_tmp_table");
DBUG_PRINT("enter",("distinct: %d save_sum_fields: %d rows_limit: %lu group: %d",
(int) distinct, (int) save_sum_fields,
