Commit 341f8221 authored by unknown's avatar unknown
Browse files

stop on NULL comparison only if it is allowed (BUG#12509) 


mysql-test/r/row.result:
  Correct NULL handling in row comporison
mysql-test/t/row.test:
  Correct NULL handling in row comporison (BUG#12509)
sql/item_cmpfunc.cc:
  stop on NULL comparison only if it is allowed
sql/item_cmpfunc.h:
  support optimisation in case of processing WHERE/HAVING, where NULL and FALSE are equal
parent 4d2bf4be

mysql-test/r/row.result

+7 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ SELECT (1,2,3)=(1,NULL,3); 
NULL

SELECT (1,2,3)=(1,NULL,0);

(1,2,3)=(1,NULL,0)

NULL

0

SELECT ROW(1,2,3)=ROW(1,2,3);

ROW(1,2,3)=ROW(1,2,3)

1
@@ -175,3 +175,9 @@ ROW(2,10) <=> ROW(3,4) 
SELECT ROW(NULL,10) <=> ROW(3,NULL);

ROW(NULL,10) <=> ROW(3,NULL)

0

SELECT ROW(1,1,1) = ROW(1,1,1) as `1`, ROW(1,1,1) = ROW(1,2,1) as `0`, ROW(1,NULL,1) = ROW(2,2,1) as `0`, ROW(1,NULL,1) = ROW(1,2,2) as `0`, ROW(1,NULL,1) = ROW(1,2,1) as `null` ;

1	0	0	0	null

1	0	0	0	NULL

select row(NULL,1)=(2,0);

row(NULL,1)=(2,0)

0

mysql-test/t/row.test

+6 −0
Original line number Diff line number Diff line
@@ -86,3 +86,9 @@ SELECT ROW(2,10) <=> ROW(3,4); 
SELECT ROW(NULL,10) <=> ROW(3,NULL);



# End of 4.1 tests



#

# Correct NULL handling in row comporison (BUG#12509)

#

SELECT ROW(1,1,1) = ROW(1,1,1) as `1`, ROW(1,1,1) = ROW(1,2,1) as `0`, ROW(1,NULL,1) = ROW(2,2,1) as `0`, ROW(1,NULL,1) = ROW(1,2,2) as `0`, ROW(1,NULL,1) = ROW(1,2,1) as `null` ;

select row(NULL,1)=(2,0);

sql/item_cmpfunc.cc

+22 −4
Original line number Diff line number Diff line
@@ -614,18 +614,36 @@ int Arg_comparator::compare_e_int_diff_signedness() 
int Arg_comparator::compare_row()

{

  int res= 0;

  bool was_null= 0;

  (*a)->bring_value();

  (*b)->bring_value();

  uint n= (*a)->cols();

  for (uint i= 0; i<n; i++)

  {

    if ((res= comparators[i].compare()))

      return res;

    res= comparators[i].compare();

    if (owner->null_value)

      return -1;

    {

      // NULL was compared

      if (owner->abort_on_null)

        return -1; // We do not need correct NULL returning

      was_null= 1;

      owner->null_value= 0;

      res= 0;  // continue comparison (maybe we will meet explicit difference)

    }

    if (res)

      return res;

  }

  if (was_null)

  {

    /*

      There was NULL(s) in comparison in some parts, but there was not

      explicit difference in other parts, so we have to return NULL

    */

    owner->null_value= 1;

    return -1;

  }

  return 0;

}



int Arg_comparator::compare_e_row()

{

sql/item_cmpfunc.h

+3 −1
Original line number Diff line number Diff line
@@ -193,10 +193,11 @@ class Item_bool_func2 :public Item_int_func 
protected:

  Arg_comparator cmp;

  String tmp_value1,tmp_value2;

  bool abort_on_null;



public:

  Item_bool_func2(Item *a,Item *b)

    :Item_int_func(a,b), cmp(tmp_arg, tmp_arg+1) {}

    :Item_int_func(a,b), cmp(tmp_arg, tmp_arg+1), abort_on_null(FALSE) {}

  void fix_length_and_dec();

  void set_cmp_func()

  {
@@ -210,6 +211,7 @@ class Item_bool_func2 :public Item_int_func 
  bool is_bool_func() { return 1; }

  CHARSET_INFO *compare_collation() { return cmp.cmp_collation.collation; }

  uint decimal_precision() const { return 1; }

  void top_level_item() { abort_on_null=1; }



  friend class  Arg_comparator;

};