Fix for bug#49199: Optimizer handles incorrectly:

field='const1' AND field='const2' in some cases

Building multiple equality predicates containing
a constant which is compared as a datetime (with a field)
we should take this fact into account and compare the 
constant with another possible constatns as datetimes 
as well.

E.g. for the
SELECT ... WHERE a='2001-01-01' AND a='2001-01-01 00:00:00'
we should compare '2001-01-01' with '2001-01-01 00:00:00' as
datetimes but not as strings.


mysql-test/r/select.result:
  Fix for bug#49199: Optimizer handles incorrectly: 
  field='const1' AND field='const2' in some cases
    - test result.
mysql-test/t/select.test:
  Fix for bug#49199: Optimizer handles incorrectly: 
  field='const1' AND field='const2' in some cases
    - test case.
sql/item_cmpfunc.cc:
  Fix for bug#49199: Optimizer handles incorrectly: 
  field='const1' AND field='const2' in some cases
    - adding a constant to Item_equal compare it as
  a datetime value with stored one if there's a 
  date[time] field in a equality predicate.
sql/item_cmpfunc.h:
  Fix for bug#49199: Optimizer handles incorrectly: 
  field='const1' AND field='const2' in some cases
    - adding a constant to Item_equal compare it as
  a datetime value with stored one if there's a 
  date[time] field in a equality predicate.
sql/sql_select.cc:
  Fix for bug#49199: Optimizer handles incorrectly: 
  field='const1' AND field='const2' in some cases
    - adding a constant to Item_equal compare it as
  a datetime value with stored one if there's a 
  date[time] field in a equality predicate.

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index db831c7030c..89bc6f9570b 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -1477,7 +1477,9 @@ class Item_equal: public Item_bool_func
   List<Item_field> fields; /* list of equal field items                    */
   Item *const_item;        /* optional constant item equal to fields items */
   cmp_item *eval_item;
+  Arg_comparator cmp;
   bool cond_false;
+  bool compare_as_dates;
 public:
   inline Item_equal()
     : Item_bool_func(), const_item(0), eval_item(0), cond_false(0)
@@ -1486,6 +1488,8 @@ public:
   Item_equal(Item *c, Item_field *f);
   Item_equal(Item_equal *item_equal);
   inline Item* get_const() { return const_item; }
+  void compare_const(Item *c);
+  void add(Item *c, Item_field *f);
   void add(Item *c);
   void add(Item_field *f);
   uint members();