MDEV-6990 GROUP_MIN_MAX optimization is not applied in some cases when it could

mysql-test/r/group_min_max.result

@@ -3727,3 +3727,57 @@ DROP TABLE t1;
 #
 # End of 10.0 tests
 #
+#
+# Start of 10.1 tests
+#
+#
+# MDEV-6990 GROUP_MIN_MAX optimization is not applied in some cases when it could
+#
+CREATE TABLE t1 (id INT NOT NULL, a DATE, KEY(id,a)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1,'2001-01-01');
+INSERT INTO t1 VALUES (1,'2001-01-02');
+INSERT INTO t1 VALUES (1,'2001-01-03');
+INSERT INTO t1 VALUES (1,'2001-01-04');
+INSERT INTO t1 VALUES (2,'2001-01-01');
+INSERT INTO t1 VALUES (2,'2001-01-02');
+INSERT INTO t1 VALUES (2,'2001-01-03');
+INSERT INTO t1 VALUES (2,'2001-01-04');
+INSERT INTO t1 VALUES (3,'2001-01-01');
+INSERT INTO t1 VALUES (3,'2001-01-02');
+INSERT INTO t1 VALUES (3,'2001-01-03');
+INSERT INTO t1 VALUES (3,'2001-01-04');
+INSERT INTO t1 VALUES (4,'2001-01-01');
+INSERT INTO t1 VALUES (4,'2001-01-02');
+INSERT INTO t1 VALUES (4,'2001-01-03');
+INSERT INTO t1 VALUES (4,'2001-01-04');
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>='2001-01-04' GROUP BY id;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	id	8	NULL	9	Using where; Using index for group-by
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104.0 GROUP BY id;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	id	8	NULL	9	Using where; Using index for group-by
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104e0 GROUP BY id;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	id	8	NULL	9	Using where; Using index for group-by
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>='2001-01-04' GROUP BY id;
+id	MIN(a)	MAX(a)
+1	2001-01-04	2001-01-04
+2	2001-01-04	2001-01-04
+3	2001-01-04	2001-01-04
+4	2001-01-04	2001-01-04
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104.0 GROUP BY id;
+id	MIN(a)	MAX(a)
+1	2001-01-04	2001-01-04
+2	2001-01-04	2001-01-04
+3	2001-01-04	2001-01-04
+4	2001-01-04	2001-01-04
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104e0 GROUP BY id;
+id	MIN(a)	MAX(a)
+1	2001-01-04	2001-01-04
+2	2001-01-04	2001-01-04
+3	2001-01-04	2001-01-04
+4	2001-01-04	2001-01-04
+DROP TABLE t1;
+#
+# End of 10.1 tests
+#

mysql-test/t/group_min_max.test

@@ -1524,3 +1524,39 @@ DROP TABLE t1;
 --echo # End of 10.0 tests
 --echo #
 
+
+--echo #
+--echo # Start of 10.1 tests
+--echo #
+
+--echo #
+--echo # MDEV-6990 GROUP_MIN_MAX optimization is not applied in some cases when it could
+--echo #
+CREATE TABLE t1 (id INT NOT NULL, a DATE, KEY(id,a)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1,'2001-01-01');
+INSERT INTO t1 VALUES (1,'2001-01-02');
+INSERT INTO t1 VALUES (1,'2001-01-03');
+INSERT INTO t1 VALUES (1,'2001-01-04');
+INSERT INTO t1 VALUES (2,'2001-01-01');
+INSERT INTO t1 VALUES (2,'2001-01-02');
+INSERT INTO t1 VALUES (2,'2001-01-03');
+INSERT INTO t1 VALUES (2,'2001-01-04');
+INSERT INTO t1 VALUES (3,'2001-01-01');
+INSERT INTO t1 VALUES (3,'2001-01-02');
+INSERT INTO t1 VALUES (3,'2001-01-03');
+INSERT INTO t1 VALUES (3,'2001-01-04');
+INSERT INTO t1 VALUES (4,'2001-01-01');
+INSERT INTO t1 VALUES (4,'2001-01-02');
+INSERT INTO t1 VALUES (4,'2001-01-03');
+INSERT INTO t1 VALUES (4,'2001-01-04');
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>='2001-01-04' GROUP BY id;
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104.0 GROUP BY id;
+EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104e0 GROUP BY id;
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>='2001-01-04' GROUP BY id;
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104.0 GROUP BY id;
+SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104e0 GROUP BY id;
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.1 tests
+--echo #

sql/field.cc

@@ -1246,6 +1246,18 @@ double Field::pos_in_interval_val_str(Field *min, Field *max, uint data_offset)
 }
 
 
+/*
+  This handles all numeric and BIT data types.
+*/ 
+bool Field::can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                       const Item *const_item)
+{
+  DBUG_ASSERT(cmp_type() != STRING_RESULT);
+  DBUG_ASSERT(cmp_type() != TIME_RESULT);
+  return const_item->cmp_type() != TIME_RESULT;
+}
+
+
 /**
   Numeric fields base class constructor.
 */
@@ -5257,6 +5269,14 @@ my_decimal *Field_temporal::val_decimal(my_decimal *d)
   return TIME_to_my_decimal(&ltime, d);
 }
 
+
+bool Field_temporal::can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                                const Item *const_item)
+{
+  return true; // Field is of TIME_RESULT, which supersedes everything else.
+}
+
+
 /****************************************************************************
 ** time type
 ** In string context: HH:MM:SS
@@ -6448,6 +6468,18 @@ uint32 Field_longstr::max_data_length() const
 }
 
 
+bool Field_longstr::can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                               const Item *const_item)
+{
+  // Can't use indexes when comparing a string to a number or a date
+  if (const_item->cmp_type() != STRING_RESULT)
+    return false;
+
+  // Don't use an index when comparing strings of different collations.
+  return charset() ==  ((Item_bool_func2*) cond)->compare_collation();
+}
+
+
 double Field_string::val_real(void)
 {
   ASSERT_COLUMN_MARKED_FOR_READ;

sql/field.h

@@ -39,6 +39,7 @@ class Relay_log_info;
 class Field;
 class Column_statistics;
 class Column_statistics_collected;
+class Item_bool_func2;
 
 enum enum_check_fields
 {
@@ -963,6 +964,9 @@ class Field
     return (double) 0.5; 
   }
 
+  virtual bool can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                          const Item *const_item);
+
   friend int cre_myisam(char * name, register TABLE *form, uint options,
 			ulonglong auto_increment_value);
   friend class Copy_field;
@@ -1154,6 +1158,8 @@ class Field_longstr :public Field_str
   int store_decimal(const my_decimal *d);
   uint32 max_data_length() const;
   bool match_collation_to_optimize_range() const { return true; }
+  bool can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                  const Item *const_item);
 };
 
 /* base class for float and double and decimal (old one) */
@@ -1581,6 +1587,12 @@ class Field_null :public Field_str {
   uint size_of() const { return sizeof(*this); }
   uint32 max_display_length() { return 4; }
   void move_field_offset(my_ptrdiff_t ptr_diff) {}
+  bool can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                  const Item *const_item)
+  {
+    DBUG_ASSERT(0);
+    return false;
+  }
 };
 
 
@@ -1613,6 +1625,8 @@ class Field_temporal: public Field {
   {
     return pos_in_interval_val_real(min, max);
   }
+  bool can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                  const Item *const_item);
 };
 
 
@@ -2650,6 +2664,18 @@ class Field_enum :public Field_str {
   virtual const uchar *unpack(uchar *to, const uchar *from,
                               const uchar *from_end, uint param_data);
 
+  bool can_optimize_group_min_max(const Item_bool_func2 *cond,
+                                  const Item *const_item)
+  {
+    /*
+      Can't use GROUP_MIN_MAX optimization for ENUM and SET,
+      because the values are stored as numbers in index,
+      while MIN() and MAX() work as strings.
+      It would return the records with min and max enum numeric indexes.
+     "Bug#45300 MAX() and ENUM type" should be fixed first.
+    */
+    return false;
+  }
 private:
   int do_save_field_metadata(uchar *first_byte);
   uint is_equal(Create_field *new_field);

sql/item_cmpfunc.h

@@ -131,6 +131,11 @@ class Item_bool_func :public Item_int_func
   bool is_bool_type() { return true; }
   void fix_length_and_dec() { decimals=0; max_length=1; }
   uint decimal_precision() const { return 1; }
+  virtual bool can_optimize_group_min_max(Item_field *min_max_arg_item,
+                                          const Item *const_item) const
+  {
+    return false;
+  }
 };
 
 
@@ -419,6 +424,12 @@ class Item_bool_rowready_func2 :public Item_bool_func2
   {
     return (*arg != NULL);     
   }
+  bool can_optimize_group_min_max(Item_field *min_max_arg_item,
+                                  const Item *const_item) const
+  {
+    return min_max_arg_item->field->can_optimize_group_min_max(this,
+                                                               const_item);
+  }
 };
 
 /**

sql/opt_range.cc

@@ -13412,39 +13412,13 @@ check_group_min_max_predicates(Item *cond, Item_field *min_max_arg_item,
         if (!simple_pred(pred, args, &inv))
           DBUG_RETURN(FALSE);
 
-        /* Check for compatible string comparisons - similar to get_mm_leaf. */
         if (args[0] && args[1] && !args[2]) // this is a binary function
         {
-          if (args[1]->cmp_type() == TIME_RESULT &&
-              min_max_arg_item->field->cmp_type() != TIME_RESULT)
+          DBUG_ASSERT(pred->is_bool_type());
+          Item_bool_func *bool_func= (Item_bool_func*) pred;
+          if (!bool_func->can_optimize_group_min_max(min_max_arg_item,
+                                                     args[1]))
             DBUG_RETURN(FALSE);
-
-          /*
-            Can't use GROUP_MIN_MAX optimization for ENUM and SET,
-            because the values are stored as numbers in index,
-            while MIN() and MAX() work as strings.
-            It would return the records with min and max enum numeric indexes.
-           "Bug#45300 MAX() and ENUM type" should be fixed first.
-          */
-          if (min_max_arg_item->field->real_type() == MYSQL_TYPE_ENUM ||
-              min_max_arg_item->field->real_type() == MYSQL_TYPE_SET)
-            DBUG_RETURN(FALSE);
-
-          if (min_max_arg_item->result_type() == STRING_RESULT &&
-              /*
-                Don't use an index when comparing strings of different collations.
-              */
-              ((args[1]->result_type() == STRING_RESULT &&
-                image_type == Field::itRAW &&
-                min_max_arg_item->field->charset() !=
-                pred->compare_collation()) ||
-             /*
-               We can't always use indexes when comparing a string index to a
-               number.
-             */
-             (args[1]->result_type() != STRING_RESULT &&
-              min_max_arg_item->field->cmp_type() != args[1]->result_type())))
-          DBUG_RETURN(FALSE);
         }
       }
       else