Commit 91d2150d authored by unknown's avatar unknown
Browse files

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.


mysql-test/r/olap.result:
  Added test case for bug #12885.
mysql-test/t/olap.test:
  Added test case for bug #12885.
sql/sql_select.cc:
  Fixed bug #12885.
  Forced inheritence of the maybe_null flag for the expressions
  containing GROUP BY attributes in selects with ROLLUP.
parent 110230be

mysql-test/r/olap.result

+13 −0
Original line number Diff line number Diff line
@@ -516,3 +516,16 @@ a b c count 
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;

mysql-test/t/olap.test

+13 −0
Original line number Diff line number Diff line
@@ -250,4 +250,17 @@ SELECT a, b, a AS c, COUNT(*) AS count FROM t1 GROUP BY a, b, c WITH ROLLUP; 


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

sql/sql_select.cc

+14 −3
Original line number Diff line number Diff line
@@ -9277,6 +9277,8 @@ void free_underlaid_joins(THD *thd, SELECT_LEX *select) 
    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 @@ void free_underlaid_joins(THD *thd, SELECT_LEX *select) 
    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 @@ static bool change_group_ref(THD *thd, Item_func *expr, ORDER *group_list, 
         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 @@ static bool change_group_ref(THD *thd, Item_func *expr, ORDER *group_list, 
            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 @@ bool JOIN::rollup_init() 
    }

    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;

      /*