bk commit into 4.1 tree (igor:1.2414) BUG#12885

[igor]

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4.1 repository of igor. When igor does a push these changes will
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ChangeSet
  1.2414 05/09/08 12:37:16 igor@stripped +3 -0
  sql_select.cc:
    Fixed bug #12885.
    Forced inheritence of the maybe_null flag for the expressions
    containing GROUP BY attributes in selects with ROLLUP.
  olap.test, olap.result:
    Added test case for bug #12885.

  sql/sql_select.cc
    1.434 05/09/08 12:33:07 igor@stripped +14 -3
    Fixed bug #12885.
    Forced inheritence of the maybe_null flag for the expressions
    containing GROUP BY attributes in selects with ROLLUP.

  mysql-test/t/olap.test
    1.18 05/09/08 12:32:12 igor@stripped +13 -0
    Added test case for bug #12885.

  mysql-test/r/olap.result
    1.21 05/09/08 12:31:31 igor@stripped +13 -0
    Added test case for bug #12885.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	igor
# Host:	rurik.mysql.com
# Root:	/home/igor/dev/mysql-4.1-0

--- 1.433/sql/sql_select.cc	Tue Aug 30 12:29:46 2005
+++ 1.434/sql/sql_select.cc	Thu Sep  8 12:33:07 2005
@@ -9277,6 +9277,8 @@
     The function replaces occurrences of group by fields in expr
     by ref objects for these fields unless they are under aggregate
     functions.
+    The function also corrects value of the the maybe_null attribute
+    for the items of all subexpressions containing group by fields.
 
   IMPLEMENTATION
     The function recursively traverses the tree of the expr expression,
@@ -9287,6 +9289,9 @@
     This substitution is needed GROUP BY queries with ROLLUP if
     SELECT list contains expressions over group by attributes.
 
+  TODO: Some functions are not null-preserving. For those functions
+    updating of the maybe_null attribute is an overkill. 
+
   EXAMPLES
     SELECT a+1 FROM t1 GROUP BY a WITH ROLLUP
     SELECT SUM(a)+a FROM t1 GROUP BY a WITH ROLLUP 
@@ -9307,6 +9312,7 @@
          arg != arg_end; arg++)
     {
       Item *item= *arg;
+      bool arg_changed= FALSE;
       if (item->type() == Item::FIELD_ITEM || item->type() == Item::REF_ITEM)
       {
         ORDER *group_tmp;
@@ -9318,15 +9324,20 @@
             if(!(new_item= new Item_ref(group_tmp->item, 0, item->name)))
               return 1;                                 // fatal_error is set
             thd->change_item_tree(arg, new_item);
-            *changed= TRUE;
+            arg_changed= TRUE;
           }
         }
       }
       else if (item->type() == Item::FUNC_ITEM)
       {
-        if (change_group_ref(thd, (Item_func *) item, group_list, changed))
+        if (change_group_ref(thd, (Item_func *) item, group_list, &arg_changed))
           return 1;
       }
+      if (arg_changed)
+      {
+        expr->maybe_null= 1;
+        *changed= TRUE;
+      }
     }
   }
   return 0;
@@ -9389,7 +9400,7 @@
     }
     if (item->type() == Item::FUNC_ITEM)
     {
-      bool changed= 0;
+      bool changed= FALSE;
       if (change_group_ref(thd, (Item_func *) item, group_list, &changed))
         return 1;
       /*

--- 1.20/mysql-test/r/olap.result	Fri Jul  1 07:39:50 2005
+++ 1.21/mysql-test/r/olap.result	Thu Sep  8 12:31:31 2005
@@ -516,3 +516,16 @@
 1	NULL	NULL	2
 NULL	NULL	NULL	2
 DROP TABLE t1;
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM (SELECT a, a + 1, COUNT(*) FROM t1 GROUP BY a WITH ROLLUP) t;
+a	a + 1	COUNT(*)
+1	2	1
+2	3	1
+NULL	NULL	2
+SELECT * FROM (SELECT a, LENGTH(a), COUNT(*) FROM t1 GROUP BY a WITH ROLLUP) t;
+a	LENGTH(a)	COUNT(*)
+1	1	1
+2	1	1
+NULL	NULL	2
+DROP TABLE t1;

--- 1.17/mysql-test/t/olap.test	Wed Jul 27 17:21:46 2005
+++ 1.18/mysql-test/t/olap.test	Thu Sep  8 12:32:12 2005
@@ -250,4 +250,17 @@
 
 DROP TABLE t1;
 
+#
+# Bug #11885:  derived table specified by a subquery with
+#              ROLLUP over expressions on not nullable group by attributes 
+#
+
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+
+SELECT * FROM (SELECT a, a + 1, COUNT(*) FROM t1 GROUP BY a WITH ROLLUP) t;
+SELECT * FROM (SELECT a, LENGTH(a), COUNT(*) FROM t1 GROUP BY a WITH ROLLUP) t;
+
+DROP TABLE t1;
+
 # End of 4.1 tests