MDEV-8703 Wrong result for SELECT..WHERE LENGTH(decimal_10_1_column)!=3 AND decimal_10_1_column=1.10

Author: Alexander Barkov

mysql-test/r/type_newdecimal.result

@@ -2078,3 +2078,72 @@ DROP TABLE t1,t2;
 #
 # End of 10.0 tests
 #
+#
+# Start of 10.1 tests
+#
+#
+# MDEV-8703 Wrong result for SELECT..WHERE LENGTH(decimal_10_1_column)!=3 AND decimal_10_1_column=1.10
+#
+CREATE TABLE t1 (a DECIMAL(10,1));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=3;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.1 instead of 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10) and (<cache>(length(1.1)) <> rand()))
+DROP TABLE t1;
+CREATE TABLE t1 (a DECIMAL(10,2));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=4;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10) and (<cache>(length(1.10)) <> rand()))
+DROP TABLE t1;
+CREATE TABLE t1 (a DECIMAL(10,3));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=5;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.100 rather than 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10) and (<cache>(length(1.100)) <> rand()))
+DROP TABLE t1;
+#
+# End of 10.1 tests
+#

mysql-test/t/type_newdecimal.test

@@ -1622,3 +1622,52 @@ DROP TABLE t1,t2;
 --echo #
 --echo # End of 10.0 tests
 --echo #
+
+--echo #
+--echo # Start of 10.1 tests
+--echo #
+
+--echo #
+--echo # MDEV-8703 Wrong result for SELECT..WHERE LENGTH(decimal_10_1_column)!=3 AND decimal_10_1_column=1.10
+--echo #
+
+# The constant scale is bigger than the field scale
+CREATE TABLE t1 (a DECIMAL(10,1));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=3;
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10;
+--echo # Notice 1.1 instead of 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+DROP TABLE t1;
+
+# The constant scale is equal to the field scale
+CREATE TABLE t1 (a DECIMAL(10,2));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=4;
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10;
+--echo # Notice 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+DROP TABLE t1;
+
+# The constant scale is smaller than the field scale
+CREATE TABLE t1 (a DECIMAL(10,3));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=5;
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10;
+--echo # Notice 1.100 rather than 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=rand() AND a=1.10;
+DROP TABLE t1;
+
+
+--echo #
+--echo # End of 10.1 tests
+--echo #

sql/field.cc

@@ -1402,22 +1402,19 @@ Item *Field_num::convert_zerofill_number_to_string(THD *thd, Item *item) const
 }
 
 
-Item *Field_num::get_equal_const_item(THD *thd, const Context &ctx,
-                                      Item_field *field_item,
-                                      Item *const_item)
+Item *Field_num::get_equal_zerofill_const_item(THD *thd, const Context &ctx,
+                                               Item_field *field_item,
+                                               Item *const_item)
 {
-  DBUG_ASSERT(const_item->const_item());
-  if ((flags & ZEROFILL_FLAG) && IS_NUM(type()))
-  {
-    if (ctx.subst_constraint() == IDENTITY_SUBST)
-      return convert_zerofill_number_to_string(thd, const_item);
-    else
-    {
-      DBUG_ASSERT(ctx.compare_type() != STRING_RESULT);
-      return field_item;
-    }
+  switch (ctx.subst_constraint()) {
+  case IDENTITY_SUBST:
+    return convert_zerofill_number_to_string(thd, const_item);
+  case ANY_SUBST:
+    break;
   }
-  return const_item;
+  DBUG_ASSERT(const_item->const_item());
+  DBUG_ASSERT(ctx.compare_type() != STRING_RESULT);
+  return field_item;
 }
 
 
@@ -3293,6 +3290,38 @@ Field_new_decimal::unpack(uchar* to, const uchar *from, const uchar *from_end,
   return from+len;
 }
 
+
+Item *Field_new_decimal::get_equal_const_item(THD *thd, const Context &ctx,
+                                              Item_field *field_item,
+                                              Item *const_item)
+{
+  if (flags & ZEROFILL_FLAG)
+    return Field_num::get_equal_zerofill_const_item(thd, ctx,
+                                                    field_item, const_item);
+  switch (ctx.subst_constraint()) {
+  case IDENTITY_SUBST:
+    if (const_item->field_type() != MYSQL_TYPE_NEWDECIMAL ||
+        const_item->decimal_scale() != decimals())
+    {
+      my_decimal *val, val_buffer, val_buffer2;
+      if (!(val= const_item->val_decimal(&val_buffer)))
+      {
+        DBUG_ASSERT(0);
+        return const_item;
+      }
+      /* Truncate or extend the decimal value to the scale of the field */
+      my_decimal_round(E_DEC_FATAL_ERROR, val, decimals(), true, &val_buffer2);
+      return new (thd->mem_root) Item_decimal(thd, field_name, &val_buffer2,
+                                              decimals(), field_length);
+    }
+    break;
+  case ANY_SUBST:
+    break;
+  }
+  return const_item;
+}
+
+
 int Field_num::store_time_dec(MYSQL_TIME *ltime, uint dec_arg)
 {
   longlong v= TIME_to_ulonglong(ltime);

sql/field.h

@@ -365,13 +365,6 @@ class Field: public Value_source
   Field(const Item &);				/* Prevent use of these */
   void operator=(Field &);
 public:
-  virtual bool can_be_substituted_to_equal_item(const Context &ctx,
-                                        const Item_equal *item);
-  virtual Item *get_equal_const_item(THD *thd, const Context &ctx,
-                                     Item_field *field_item, Item *const_item)
-  {
-    return const_item;
-  }
   static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
   { return alloc_root(mem_root, size); }
   static void *operator new(size_t size) throw ()
@@ -1107,6 +1100,13 @@ class Field: public Value_source
   */
   virtual bool test_if_equality_guarantees_uniqueness(const Item *const_item)
                                                       const;
+  virtual bool can_be_substituted_to_equal_item(const Context &ctx,
+                                        const Item_equal *item);
+  virtual Item *get_equal_const_item(THD *thd, const Context &ctx,
+                                     Item_field *field_item, Item *const_item)
+  {
+    return const_item;
+  }
   virtual bool can_optimize_keypart_ref(const Item_bool_func *cond,
                                         const Item *item) const;
   virtual bool can_optimize_hash_join(const Item_bool_func *cond,
@@ -1208,9 +1208,10 @@ class Field: public Value_source
 class Field_num :public Field {
 protected:
   Item *convert_zerofill_number_to_string(THD *thd, Item *item) const;
+  Item *get_equal_zerofill_const_item(THD *thd, const Context &ctx,
+                                      Item_field *field_item,
+                                      Item *const_item);
 public:
-  Item *get_equal_const_item(THD *thd, const Context &ctx,
-                             Item_field *field_item, Item *const_item);
   const uint8 dec;
   bool zerofill,unsigned_flag;	// Purify cannot handle bit fields
   Field_num(uchar *ptr_arg,uint32 len_arg, uchar *null_ptr_arg,
@@ -1222,6 +1223,13 @@ class Field_num :public Field {
   uint repertoire(void) const { return MY_REPERTOIRE_NUMERIC; }
   CHARSET_INFO *charset(void) const { return &my_charset_numeric; }
   void prepend_zeros(String *value) const;
+  Item *get_equal_const_item(THD *thd, const Context &ctx,
+                             Item_field *field_item, Item *const_item)
+  {
+    return (flags & ZEROFILL_FLAG) ?
+           get_equal_zerofill_const_item(thd, ctx, field_item, const_item) :
+           const_item;
+  }
   void add_zerofill_and_unsigned(String &res) const;
   friend class Create_field;
   void make_field(Send_field *);
@@ -1440,6 +1448,8 @@ class Field_new_decimal :public Field_num {
   uint is_equal(Create_field *new_field);
   virtual const uchar *unpack(uchar* to, const uchar *from, const uchar *from_end, uint param_data);
   static Field *create_from_item(MEM_ROOT *root, Item *);
+  Item *get_equal_const_item(THD *thd, const Context &ctx,
+                             Item_field *field_item, Item *const_item);
 };