bk commit into 5.0 tree (evgen:1.2539) BUG#31095

[eugene]

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ChangeSet@stripped, 2007-09-29 00:22:54+00:00, evgen@stripped +3 -0
  Bug#31095: Unexpected NULL constant caused server crash.
  
  The Item_func_rollup_const class is used for wrapping constants to avoid
  wrong result for ROLLUP queries with DISTINCT and a constant in the select
  list. This class is also used to wrap up a NULL constant but its null_value
  wasn't set accordingly. This led to a server crash.
  
  Now the null_value of an object of the Item_func_rollup_const class is set
  by the JOIN::rollup_init function when the object is used to wrap a NULL
  constant.

  mysql-test/r/olap.result@stripped, 2007-09-29 00:20:01+00:00, evgen@stripped +11 -0
    Added a test case for the bug#31095: Unexpected NULL constant caused server crash.

  mysql-test/t/olap.test@stripped, 2007-09-29 00:19:47+00:00, evgen@stripped +9 -0
    Added a test case for the bug#31095: Unexpected NULL constant caused server crash.

  sql/sql_select.cc@stripped, 2007-09-29 00:20:14+00:00, evgen@stripped +2 -0
    Bug#31095: Unexpected NULL constant caused server crash.
    Now the null_value of an object of the Item_func_rollup_const class is set
    by the JOIN::rollup_init function when the object is used to wrap a NULL
    constant.

diff -Nrup a/mysql-test/r/olap.result b/mysql-test/r/olap.result
--- a/mysql-test/r/olap.result	2007-05-30 06:55:36 +00:00
+++ b/mysql-test/r/olap.result	2007-09-29 00:20:01 +00:00
@@ -715,3 +715,14 @@ a	SUM(a)
 4	4
 NULL	14
 DROP TABLE t1;
+#
+# Bug#31095: Unexpected NULL value constant server crash.
+#
+create table t1(a int);
+insert into t1 values (1),(2),(3);
+select a,count(a) from t1 group by null with rollup;
+a	count(a)
+1	3
+1	3
+drop table t1;
+##############################################################
diff -Nrup a/mysql-test/t/olap.test b/mysql-test/t/olap.test
--- a/mysql-test/t/olap.test	2007-04-30 01:32:57 +00:00
+++ b/mysql-test/t/olap.test	2007-09-29 00:19:47 +00:00
@@ -358,3 +358,12 @@ SELECT * FROM (SELECT a, SUM(a) FROM t1 
 
 DROP TABLE t1;
 
+--echo #
+--echo # Bug#31095: Unexpected NULL constant caused server crash.
+--echo #
+create table t1(a int);
+insert into t1 values (1),(2),(3);
+select a,count(a) from t1 group by null with rollup;
+drop table t1;
+--echo ##############################################################
+
diff -Nrup a/sql/sql_select.cc b/sql/sql_select.cc
--- a/sql/sql_select.cc	2007-09-24 12:34:09 +00:00
+++ b/sql/sql_select.cc	2007-09-29 00:20:14 +00:00
@@ -14734,6 +14734,8 @@ bool JOIN::rollup_init()
           if (!new_item)
             return 1;
           new_item->fix_fields(thd, (Item **) 0);
+          /* The item could be a NULL constant. */
+          new_item->null_value= item->null_value;
           thd->change_item_tree(it.ref(), new_item);
           for (ORDER *tmp= group_tmp; tmp; tmp= tmp->next)
           {