MDEV-12546 Wrong metadata or data type for string user variables

mysql-test/r/last_value.result

@@ -21,7 +21,7 @@ a	b	c	d
 DROP TABLE t1;
 SELECT LAST_VALUE(@last_a:=1,@last_b:=1);
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def					LAST_VALUE(@last_a:=1,@last_b:=1)	8	1	1	N	32897	0	63
+def					LAST_VALUE(@last_a:=1,@last_b:=1)	3	1	1	N	32897	0	63
 LAST_VALUE(@last_a:=1,@last_b:=1)
 1
 select @last_b;
@@ -46,7 +46,7 @@ LAST_VALUE(@last_a:=1,@last_b:="hello")
 hello
 select @last_b;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def					@last_b	250	16777215	5	Y	0	39	8
+def					@last_b	251	16777215	5	Y	0	39	8
 @last_b
 hello
 SELECT date(LAST_VALUE(@last_a:=1,@last_b:="2001-02-03"));
@@ -56,7 +56,7 @@ date(LAST_VALUE(@last_a:=1,@last_b:="2001-02-03"))
 2001-02-03
 select @last_b;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def					@last_b	250	16777215	10	Y	0	39	8
+def					@last_b	251	16777215	10	Y	0	39	8
 @last_b
 2001-02-03
 SELECT LAST_VALUE(@last_a:=1,@last_b:="2001-02-03",NULL);
@@ -66,7 +66,7 @@ LAST_VALUE(@last_a:=1,@last_b:="2001-02-03",NULL)
 NULL
 select @last_b;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def					@last_b	250	16777215	10	Y	0	39	8
+def					@last_b	251	16777215	10	Y	0	39	8
 @last_b
 2001-02-03
 SELECT LAST_VALUE();

mysql-test/r/metadata.result

@@ -772,3 +772,33 @@ def					ROUND(11111111)	3	8	0	N	32897	0	63
 def					ROUND(111111111)	3	9	0	N	32897	0	63
 def					ROUND(1111111111)	8	10	0	N	32897	0	63
 ROUND(1)	ROUND(11)	ROUND(111)	ROUND(1111)	ROUND(11111)	ROUND(111111)	ROUND(1111111)	ROUND(11111111)	ROUND(111111111)	ROUND(1111111111)
+#
+# MDEV-12546 Wrong metadata or data type for string user variables
+#
+SET @a='test';
+SELECT @a;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					@a	251	16777215	4	Y	0	39	8
+@a
+test
+CREATE TABLE t1 AS SELECT @a;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `@a` longtext DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
+SELECT @b1:=10, @b2:=@b2:=111111111111;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					@b1:=10	3	2	2	N	32897	0	63
+def					@b2:=@b2:=111111111111	8	12	12	N	32897	0	63
+@b1:=10	@b2:=@b2:=111111111111
+10	111111111111
+CREATE TABLE t1 AS SELECT @b1:=10, @b2:=111111111111;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `@b1:=10` int(2) NOT NULL,
+  `@b2:=111111111111` bigint(12) NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;

mysql-test/t/metadata.test

@@ -465,3 +465,21 @@ SELECT
   ROUND(1111111111) LIMIT 0;
 
 --disable_metadata
+
+--echo #
+--echo # MDEV-12546 Wrong metadata or data type for string user variables
+--echo #
+SET @a='test';
+--enable_metadata
+SELECT @a;
+--disable_metadata
+CREATE TABLE t1 AS SELECT @a;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+--enable_metadata
+SELECT @b1:=10, @b2:=@b2:=111111111111;
+--disable_metadata
+CREATE TABLE t1 AS SELECT @b1:=10, @b2:=111111111111;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;

sql/item.h

@@ -566,6 +566,15 @@ class Item: public Value_source,
 
   SEL_TREE *get_mm_tree_for_const(RANGE_OPT_PARAM *param);
 
+  /**
+    Create a field based on the exact data type handler.
+  */
+  Field *create_table_field_from_handler(TABLE *table)
+  {
+    const Type_handler *h= type_handler();
+    return h->make_and_init_table_field(&name, Record_addr(maybe_null),
+                                        *this, table);
+  }
   /**
     Create a field based on field_type of argument.
     This is used to create a field for

sql/item_func.cc

@@ -4351,8 +4351,27 @@ bool Item_func_set_user_var::fix_fields(THD *thd, Item **ref)
     m_var_entry->set_charset(args[0]->collation.derivation == DERIVATION_NUMERIC ?
                              default_charset() : args[0]->collation.collation);
   collation.set(m_var_entry->charset(), DERIVATION_IMPLICIT);
-  set_handler_by_result_type(args[0]->result_type(),
-                             max_length, collation.collation);
+  switch (args[0]->result_type()) {
+  case STRING_RESULT:
+  case TIME_RESULT:
+    set_handler(type_handler_long_blob.
+                type_handler_adjusted_to_max_octet_length(max_length,
+                                                          collation.collation));
+    break;
+  case REAL_RESULT:
+    set_handler(&type_handler_double);
+    break;
+  case INT_RESULT:
+    set_handler(Type_handler::type_handler_long_or_longlong(max_char_length()));
+    break;
+  case DECIMAL_RESULT:
+    set_handler(&type_handler_newdecimal);
+    break;
+  case ROW_RESULT:
+    DBUG_ASSERT(0);
+    set_handler(&type_handler_row);
+    break;
+  }
   if (thd->lex->current_select)
   {
     /*
@@ -5258,7 +5277,6 @@ void Item_func_get_user_var::fix_length_and_dec()
       break;
     case STRING_RESULT:
       max_length= MAX_BLOB_WIDTH - 1;
-      set_handler(&type_handler_medium_blob);
       break;
     case DECIMAL_RESULT:
       fix_char_length(DECIMAL_MAX_STR_LENGTH);

sql/item_func.h

@@ -2242,9 +2242,9 @@ class Item_func_user_var :public Item_hybrid_func
     :Item_hybrid_func(thd, item),
     m_var_entry(item->m_var_entry), name(item->name) { }
   Field *create_tmp_field(bool group, TABLE *table)
-  { return Item::create_tmp_field(group, table); }
+  { return create_table_field_from_handler(table); }
   Field *create_field_for_create_select(TABLE *table)
-  { return Item::create_field_for_create_select(table); }
+  { return create_table_field_from_handler(table); }
   bool check_vcol_func_processor(void *arg);
 };
 
@@ -2347,14 +2347,6 @@ class Item_func_get_user_var :public Item_func_user_var,
   my_decimal *val_decimal(my_decimal*);
   String *val_str(String* str);
   void fix_length_and_dec();
-  Field *create_field_for_create_select(TABLE *table)
-  {
-    return Type_handler_hybrid_field_type::cmp_type() == STRING_RESULT ?
-      type_handler_long_blob.make_and_init_table_field(&(Item::name),
-                                                       Record_addr(maybe_null),
-                                                       *this, table) :
-      create_tmp_field(false, table);
-  }
   virtual void print(String *str, enum_query_type query_type);
   /*
     We must always return variables as strings to guard against selects of type