fixed union types merging and table related metadata (BUG#8824)

mysql-test/r/func_group.result

@@ -747,7 +747,7 @@ insert into t1 values (now());
 create table t2 select f2 from (select max(now()) f2 from t1) a;
 show columns from t2;
 Field	Type	Null	Key	Default	Extra
-f2	datetime			0000-00-00 00:00:00	
+f2	datetime	YES		NULL	
 drop table t2;
 create table t2 select f2 from (select now() f2 from t1) a;
 show columns from t2;

mysql-test/r/metadata.result

@@ -55,8 +55,33 @@ id	data	data
 2	female	no
 select t1.id from t1 union select t2.id from t2;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Name	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def	test	t1	t1	id	id	1	3	1	Y	32768	0	63
+def				id	id	1	4	1	Y	32768	0	63
 id
 1
 2
 drop table t1,t2;
+create table t1 ( a int, b varchar(30), primary key(a));
+insert into t1 values (1,'one');
+insert into t1 values (2,'two');
+set @arg00=1 ;
+select @arg00 FROM t1 where a=1 union distinct select 1 FROM t1 where a=1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Name	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def				@arg00	@arg00	8	20	1	Y	32768	0	63
+@arg00
+1
+select * from (select @arg00) aaa;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Name	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def			aaa	@arg00	@arg00	8	20	1	Y	32768	0	63
+@arg00
+1
+select 1 union select 1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Name	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def				1	1	8	20	1	N	32769	0	63
+1
+1
+select * from (select 1 union select 1) aaa;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Name	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def			aaa	1	1	8	20	1	N	32769	0	63
+1
+1
+drop table t1;

mysql-test/r/union.result

@@ -655,7 +655,7 @@ f
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `f` binary(24) default NULL
+  `f` varbinary(24) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT y from t2 UNION select da from t2;
@@ -666,7 +666,7 @@ y
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `y` binary(10) default NULL
+  `y` varbinary(10) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT y from t2 UNION select dt from t2;
@@ -677,7 +677,7 @@ y
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `y` binary(19) default NULL
+  `y` varbinary(19) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT da from t2 UNION select dt from t2;
@@ -699,7 +699,7 @@ testc
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `dt` binary(19) default NULL
+  `dt` varbinary(19) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT dt from t2 UNION select sv from t2;
@@ -710,7 +710,7 @@ testv
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `dt` binary(19) default NULL
+  `dt` varbinary(19) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT sc from t2 UNION select sv from t2;
@@ -732,7 +732,7 @@ tetetetetest
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `dt` blob
+  `dt` longblob
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT sv from t2 UNION select b from t2;
@@ -755,7 +755,7 @@ tetetetetest
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `i` blob
+  `i` longblob
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT sv from t2 UNION select tx from t2;
@@ -766,7 +766,7 @@ teeeeeeeeeeeest
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `sv` text
+  `sv` longtext
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 create table t1 SELECT b from t2 UNION select tx from t2;
@@ -1069,7 +1069,7 @@ create table t1 as
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `_latin1'test' collate latin1_bin` char(4) character set latin1 collate latin1_bin NOT NULL default ''
+  `_latin1'test' collate latin1_bin` varchar(4) character set latin1 collate latin1_bin NOT NULL default ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 select count(*) from t1;
 count(*)
@@ -1082,7 +1082,7 @@ create table t1 as
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `test` char(4) character set latin1 collate latin1_bin NOT NULL default ''
+  `test` varchar(4) character set latin1 collate latin1_bin NOT NULL default ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 select count(*) from t1;
 count(*)
@@ -1095,7 +1095,7 @@ create table t1 as
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `test` char(4) character set latin1 collate latin1_bin NOT NULL default ''
+  `test` varchar(4) character set latin1 collate latin1_bin NOT NULL default ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 select count(*) from t1;
 count(*)
@@ -1195,3 +1195,38 @@ a	b
 2	b
 3	c
 drop table t1;
+CREATE TABLE t1 (
+a ENUM('ä','ö','ü') character set utf8 not null default 'ü',
+b ENUM("one", "two") character set utf8,
+c ENUM("one", "two")
+);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` enum('ä','ö','ü') character set utf8 NOT NULL default 'ü',
+  `b` enum('one','two') character set utf8 default NULL,
+  `c` enum('one','two') default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+insert into t1 values ('ä', 'one', 'one'), ('ö', 'two', 'one'), ('ü', NULL, NULL);
+create table t2 select NULL union select a from t1;
+show columns from t2;
+Field	Type	Null	Key	Default	Extra
+NULL	enum('ä','ö','ü')	YES		NULL	
+drop table t2;
+create table t2 select a from t1 union select NULL;
+show columns from t2;
+Field	Type	Null	Key	Default	Extra
+a	enum('ä','ö','ü')	YES		NULL	
+drop table t2;
+create table t2 select a from t1 union select a from t1;
+show columns from t2;
+Field	Type	Null	Key	Default	Extra
+a	char(1)				
+drop table t2;
+create table t2 select a from t1 union select c from t1;
+ERROR HY000: Illegal mix of collations (utf8_general_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation 'UNION'
+create table t2 select a from t1 union select b from t1;
+show columns from t2;
+Field	Type	Null	Key	Default	Extra
+a	varchar(3)	YES		NULL	
+drop table t2, t1;

mysql-test/t/metadata.test

@@ -34,4 +34,17 @@ select t1.id, t1.data, t2.data from t1, t2 where t1.id = t2.id order by t1.id;
 select t1.id from t1 union select t2.id from t2;
 drop table t1,t2;
 
+#
+# variables union and derived tables metadata test
+#
+create table t1 ( a int, b varchar(30), primary key(a));
+insert into t1 values (1,'one');
+insert into t1 values (2,'two');
+set @arg00=1 ;
+select @arg00 FROM t1 where a=1 union distinct select 1 FROM t1 where a=1;
+select * from (select @arg00) aaa;
+select 1 union select 1;
+select * from (select 1 union select 1) aaa;
+drop table t1;
+
 --disable_metadata

mysql-test/t/union.test

@@ -711,3 +711,28 @@ select * from ((select * from t1 limit 1) union (select * from t1 limit 1) union
 select * from ((((select * from t1))) union (select * from t1) union (select * from t1)) a;
 select * from ((select * from t1) union (((select * from t1))) union (select * from t1)) a;
 drop table t1;
+
+#
+# Enum merging test
+#
+CREATE TABLE t1 (
+  a ENUM('ä','ö','ü') character set utf8 not null default 'ü',
+  b ENUM("one", "two") character set utf8,
+  c ENUM("one", "two")
+);
+show create table t1;
+insert into t1 values ('ä', 'one', 'one'), ('ö', 'two', 'one'), ('ü', NULL, NULL);
+create table t2 select NULL union select a from t1;
+show columns from t2;
+drop table t2;
+create table t2 select a from t1 union select NULL;
+show columns from t2;
+drop table t2;
+create table t2 select a from t1 union select a from t1;
+show columns from t2;
+drop table t2;
+-- error 1267
+create table t2 select a from t1 union select c from t1;
+create table t2 select a from t1 union select b from t1;
+show columns from t2;
+drop table t2, t1;

sql/field.h

@@ -31,6 +31,17 @@ class Protocol;
 struct st_cache_field;
 void field_conv(Field *to,Field *from);
 
+inline uint get_enum_pack_length(int elements)
+{
+  return elements < 256 ? 1 : 2;
+}
+
+inline uint get_set_pack_length(int elements)
+{
+  uint len= (elements + 7) / 8;
+  return len > 4 ? 8 : len;
+}
+
 class Field
 {
   Field(const Item &);				/* Prevent use of these */
@@ -75,17 +86,6 @@ public:
     GEOM_GEOMETRYCOLLECTION = 7
   };
   enum imagetype { itRAW, itMBR};
-  enum field_cast_enum
-  {
-    FIELD_CAST_STOP, FIELD_CAST_DECIMAL, FIELD_CAST_TINY, FIELD_CAST_SHORT,
-    FIELD_CAST_MEDIUM, FIELD_CAST_LONG, FIELD_CAST_LONGLONG,
-    FIELD_CAST_FLOAT, FIELD_CAST_DOUBLE,
-    FIELD_CAST_NULL,
-    FIELD_CAST_TIMESTAMP, FIELD_CAST_YEAR, FIELD_CAST_DATE, FIELD_CAST_NEWDATE,
-    FIELD_CAST_TIME, FIELD_CAST_DATETIME,
-    FIELD_CAST_STRING, FIELD_CAST_VARSTRING, FIELD_CAST_BLOB,
-    FIELD_CAST_GEOM, FIELD_CAST_ENUM, FIELD_CAST_SET
-  };
 
   utype		unireg_check;
   uint32	field_length;		// Length of field
@@ -119,6 +119,8 @@ public:
   virtual String *val_str(String*,String *)=0;
   virtual Item_result result_type () const=0;
   virtual Item_result cmp_type () const { return result_type(); }
+  static enum_field_types field_type_merge(enum_field_types, enum_field_types);
+  static Item_result result_merge_type(enum_field_types);
   bool eq(Field *field) { return ptr == field->ptr && null_ptr == field->null_ptr; }
   virtual bool eq_def(Field *field);
   virtual uint32 pack_length() const { return (uint32) field_length; }
@@ -290,8 +292,6 @@ public:
                             int cuted_increment);
   void set_datetime_warning(const uint level, const uint code, 
                             double nr, timestamp_type ts_type);
-  virtual field_cast_enum field_cast_type()= 0;
-  bool field_cast_compatible(field_cast_enum type);
   /* maximum possible display length */
   virtual uint32 max_length()= 0;
   friend bool reopen_table(THD *,struct st_table *,bool);
@@ -398,7 +398,6 @@ public:
   bool zero_pack() const { return 0; }
   void sql_type(String &str) const;
   uint32 max_length() { return field_length; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_DECIMAL; }
 };
 
 
@@ -430,7 +429,6 @@ public:
   uint32 pack_length() const { return 1; }
   void sql_type(String &str) const;
   uint32 max_length() { return 4; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_TINY; }
 };
 
 
@@ -467,7 +465,6 @@ public:
   uint32 pack_length() const { return 2; }
   void sql_type(String &str) const;
   uint32 max_length() { return 6; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_SHORT; }
 };
 
 
@@ -499,7 +496,6 @@ public:
   uint32 pack_length() const { return 3; }
   void sql_type(String &str) const;
   uint32 max_length() { return 8; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_MEDIUM; }
 };
 
 
@@ -536,7 +532,6 @@ public:
   uint32 pack_length() const { return 4; }
   void sql_type(String &str) const;
   uint32 max_length() { return 11; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_LONG; }
 };
 
 
@@ -576,7 +571,6 @@ public:
   void sql_type(String &str) const;
   bool can_be_compared_as_longlong() const { return TRUE; }
   uint32 max_length() { return 20; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_LONGLONG; }
 };
 #endif
 
@@ -611,7 +605,6 @@ public:
   uint32 pack_length() const { return sizeof(float); }
   void sql_type(String &str) const;
   uint32 max_length() { return 24; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_FLOAT; }
 };
 
 
@@ -646,7 +639,6 @@ public:
   uint32 pack_length() const { return sizeof(double); }
   void sql_type(String &str) const;
   uint32 max_length() { return 53; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_DOUBLE; }
 };
 
 
@@ -677,7 +669,6 @@ public:
   void sql_type(String &str) const;
   uint size_of() const { return sizeof(*this); }
   uint32 max_length() { return 4; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_NULL; }
 };
 
 
@@ -729,7 +720,6 @@ public:
   }
   bool get_date(TIME *ltime,uint fuzzydate);
   bool get_time(TIME *ltime);
-  field_cast_enum field_cast_type() { return FIELD_CAST_TIMESTAMP; }
   timestamp_auto_set_type get_auto_set_type() const;
 };
 
@@ -753,7 +743,6 @@ public:
   bool send_binary(Protocol *protocol);
   void sql_type(String &str) const;
   bool can_be_compared_as_longlong() const { return TRUE; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_YEAR; }
 };
 
 
@@ -786,7 +775,6 @@ public:
   void sql_type(String &str) const;
   bool can_be_compared_as_longlong() const { return TRUE; }
   bool zero_pack() const { return 1; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_DATE; }
 };
 
 class Field_newdate :public Field_str {
@@ -818,7 +806,6 @@ public:
   bool zero_pack() const { return 1; }
   bool get_date(TIME *ltime,uint fuzzydate);
   bool get_time(TIME *ltime);
-  field_cast_enum field_cast_type() { return FIELD_CAST_NEWDATE; }
 };
 
 
@@ -853,7 +840,6 @@ public:
   void sql_type(String &str) const;
   bool can_be_compared_as_longlong() const { return TRUE; }
   bool zero_pack() const { return 1; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_TIME; }
 };
 
 
@@ -891,7 +877,6 @@ public:
   bool zero_pack() const { return 1; }
   bool get_date(TIME *ltime,uint fuzzydate);
   bool get_time(TIME *ltime);
-  field_cast_enum field_cast_type() { return FIELD_CAST_DATETIME; }
 };
 
 
@@ -937,7 +922,6 @@ public:
   enum_field_types real_type() const { return FIELD_TYPE_STRING; }
   bool has_charset(void) const
   { return charset() == &my_charset_bin ? FALSE : TRUE; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_STRING; }
 };
 
 
@@ -986,7 +970,6 @@ public:
   enum_field_types real_type() const { return FIELD_TYPE_VAR_STRING; }
   bool has_charset(void) const
   { return charset() == &my_charset_bin ? FALSE : TRUE; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_VARSTRING; }
 };
 
 
@@ -1081,7 +1064,6 @@ public:
   uint size_of() const { return sizeof(*this); }
   bool has_charset(void) const
   { return charset() == &my_charset_bin ? FALSE : TRUE; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_BLOB; }
   uint32 max_length();
 };
 
@@ -1111,7 +1093,6 @@ public:
 
   void get_key_image(char *buff,uint length, CHARSET_INFO *cs,imagetype type);
   void set_key_image(char *buff,uint length, CHARSET_INFO *cs);
-  field_cast_enum field_cast_type() { return FIELD_CAST_GEOM; }
 };
 #endif /*HAVE_SPATIAL*/
 
@@ -1155,7 +1136,6 @@ public:
   bool has_charset(void) const { return TRUE; }
   /* enum and set are sorted as integers */
   CHARSET_INFO *sort_charset(void) const { return &my_charset_bin; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_ENUM; }
 };
 
 
@@ -1181,7 +1161,6 @@ public:
   void sql_type(String &str) const;
   enum_field_types real_type() const { return FIELD_TYPE_SET; }
   bool has_charset(void) const { return TRUE; }
-  field_cast_enum field_cast_type() { return FIELD_CAST_SET; }
 };
 
 
@@ -1268,7 +1247,6 @@ int set_field_to_null(Field *field);
 int set_field_to_null_with_conversions(Field *field, bool no_conversions);
 bool test_if_int(const char *str, int length, const char *int_end,
 		 CHARSET_INFO *cs);
-bool field_types_to_be_kept(enum_field_types field_type);
 
 /*
   The following are for the interface with the .frm file

sql/item.cc

@@ -1700,10 +1700,10 @@ Field *Item::tmp_table_field_from_field_type(TABLE *table)
   case MYSQL_TYPE_NULL:
     return new Field_null((char*) 0, max_length, Field::NONE,
 			  name, table, &my_charset_bin);
-  case MYSQL_TYPE_NEWDATE:
   case MYSQL_TYPE_INT24:
     return new Field_medium((char*) 0, max_length, null_ptr, 0, Field::NONE,
 			    name, table, 0, unsigned_flag);
+  case MYSQL_TYPE_NEWDATE:
   case MYSQL_TYPE_DATE:
     return new Field_date(maybe_null, name, table, &my_charset_bin);
   case MYSQL_TYPE_TIME:
@@ -2701,204 +2701,268 @@ void Item_cache_row::bring_value()
 }
 
 
-/*
+Item_type_holder::Item_type_holder(THD *thd, Item *item)
-  Returns field for temporary table dependind on item type
+  :Item(thd, item), enum_set_typelib(0), fld_type(get_real_type(item))
-
-  SYNOPSIS
-    get_holder_example_field()
-    thd            - thread handler
-    item           - pointer to item
-    table          - empty table object
-
-  NOTE
-    It is possible to return field for Item_func 
-    items only if field type of this item is 
-    date or time or datetime type.
-    also see function field_types_to_be_kept() from
-    field.cc
-
-  RETURN
-    # - field
-    0 - no field
-*/
-
-Field *get_holder_example_field(THD *thd, Item *item, TABLE *table)
-{
-  DBUG_ASSERT(table);
-
-  Item_func *tmp_item= 0;
-  if (item->type() == Item::FIELD_ITEM)
-    return (((Item_field*) item)->field);
-  if (item->type() == Item::FUNC_ITEM)
-    tmp_item= (Item_func *) item;
-  else if (item->type() == Item::SUM_FUNC_ITEM)
-  {
-    Item_sum *item_sum= (Item_sum *) item;
-    if (item_sum->keep_field_type())
-    {
-      if (item_sum->args[0]->type() == Item::FIELD_ITEM)
-        return (((Item_field*) item_sum->args[0])->field);
-      if (item_sum->args[0]->type() == Item::FUNC_ITEM)
-        tmp_item= (Item_func *) item_sum->args[0];
-    }
-  }
-  return (tmp_item && field_types_to_be_kept(tmp_item->field_type()) ?
-          tmp_item->tmp_table_field(table) : 0);
-}
-
-
-Item_type_holder::Item_type_holder(THD *thd, Item *item, TABLE *table)
-  :Item(thd, item), item_type(item->result_type()),
-   orig_type(item_type)
 {
   DBUG_ASSERT(item->fixed);
 
-  /*
+  max_length= display_length(item);
-    It is safe assign pointer on field, because it will be used just after
-    all JOIN::prepare calls and before any SELECT execution
-  */
-  field_example= get_holder_example_field(thd, item, table);
-  max_length= real_length(item);
   maybe_null= item->maybe_null;
   collation.set(item->collation);
+  get_full_info(item);
 }
 
 
 /*
-  STRING_RESULT, REAL_RESULT, INT_RESULT, ROW_RESULT
+  Return expression type of Item_type_holder
-
-  ROW_RESULT should never appear in Item_type_holder::join_types,
-  but it is included in following table just to make table full
-  (there DBUG_ASSERT in function to catch ROW_RESULT)
-*/
-static Item_result type_convertor[4][4]=
-{{STRING_RESULT, STRING_RESULT, STRING_RESULT, ROW_RESULT},
- {STRING_RESULT, REAL_RESULT,   REAL_RESULT,   ROW_RESULT},
- {STRING_RESULT, REAL_RESULT,   INT_RESULT,    ROW_RESULT},
- {ROW_RESULT,    ROW_RESULT,    ROW_RESULT,    ROW_RESULT}};
-
-
-/*
-  Values of 'from' field can be stored in 'to' field.
 
   SYNOPSIS
-    is_attr_compatible()
+    Item_type_holder::result_type()
-    from        Item which values should be saved
-    to          Item where values should be saved
 
   RETURN
-    1   can be saved
+     Item_result (type of internal MySQL expression result)
-    0   can not be saved
 */
 
-inline bool is_attr_compatible(Item *from, Item *to)
+Item_result Item_type_holder::result_type() const
 {
-  return ((to->max_length >= from->max_length) &&
+  return Field::result_merge_type(fld_type);
-          (to->maybe_null || !from->maybe_null) &&
-          (to->result_type() != STRING_RESULT ||
-           from->result_type() != STRING_RESULT ||
-          (from->collation.collation == to->collation.collation)));
 }
 
 
-bool Item_type_holder::join_types(THD *thd, Item *item, TABLE *table)
-{
-  uint32 new_length= real_length(item);
-  bool use_new_field= 0, use_expression_type= 0;
-  Item_result new_result_type= type_convertor[item_type][item->result_type()];
-  Field *field= get_holder_example_field(thd, item, table);
-  bool item_is_a_field= (field != NULL);
 /*
-    Check if both items point to fields: in this case we
+  Find real field type of item
-    can adjust column types of result table in the union smartly.
+
+  SYNOPSIS
+    Item_type_holder::get_real_type()
+
+  RETURN
+    type of field which should be created to store item value
 */
-  if (field_example && item_is_a_field)
+
+enum_field_types Item_type_holder::get_real_type(Item *item)
 {
-    /* Can 'field_example' field store data of the column? */
+  switch(item->type())
-    if ((use_new_field=
+  {
-         (!field->field_cast_compatible(field_example->field_cast_type()) ||
+  case FIELD_ITEM:
-          !is_attr_compatible(item, this))))
   {
     /*
-        The old field can't store value of the new field.
+      Item_fields::field_type ask Field_type() but sometimes field return
-        Check if the new field can store value of the old one.
+      a different type, like for enum/set, so we need to ask real type.
     */
-      use_expression_type|=
+    Field *field= ((Item_field *) item)->field;
-        (!field_example->field_cast_compatible(field->field_cast_type()) ||
+    enum_field_types type= field->real_type();
-         !is_attr_compatible(this, item));
+    /* work around about varchar type field detection */
+    if (type == MYSQL_TYPE_STRING && field->type() == MYSQL_TYPE_VAR_STRING)
+      return MYSQL_TYPE_VAR_STRING;
+    return type;
   }
-  }
+  case SUM_FUNC_ITEM:
-  else if (field_example || item_is_a_field)
   {
     /*
-      Expression types can't be mixed with field types, we have to use
+      Argument of aggregate function sometimes should be asked about field
-      expression types.
+      type
     */
-    use_new_field= 1;                           // make next if test easier
+    Item_sum *item_sum= (Item_sum *) item;
-    use_expression_type= 1;
+    if (item_sum->keep_field_type())
+      return get_real_type(item_sum->args[0]);
+    break;
+  }
+  case FUNC_ITEM:
+    if (((Item_func *) item)->functype() == Item_func::VAR_VALUE_FUNC)
+    {
+      /*
+        There are work around of problem with changing variable type on the
+        fly and variable always report "string" as field type to get
+        acceptable information for client in send_field, so we make field
+        type from expression type.
+      */
+      switch (item->result_type())
+      {
+      case STRING_RESULT:
+        return MYSQL_TYPE_VAR_STRING;
+      case INT_RESULT:
+        return MYSQL_TYPE_LONGLONG;
+      case REAL_RESULT:
+        return MYSQL_TYPE_DOUBLE;
+      case ROW_RESULT:
+      default:
+        DBUG_ASSERT(0);
+        return MYSQL_TYPE_VAR_STRING;
+      }
+    }
+    break;
+  default:
+    break;
+  }
+  return item->field_type();
 }
 
-  /* Check whether size/type of the result item should be changed */
+/*
-  if (use_new_field ||
+  Find field type which can carry current Item_type_holder type and
-      (new_result_type != item_type) || (new_length > max_length) ||
+  type of given Item.
-      (!maybe_null && item->maybe_null) ||
+
-      (item_type == STRING_RESULT && 
+  SYNOPSIS
-       collation.collation != item->collation.collation))
+    Item_type_holder::join_types()
+    thd     thread handler
+    item    given item to join its parameters with this item ones
+
+  RETURN
+    TRUE   error - types are incompatible
+    FALSE  OK
+*/
+
+bool Item_type_holder::join_types(THD *thd, Item *item)
+{
+  max_length= max(max_length, display_length(item));
+  fld_type= Field::field_type_merge(fld_type, get_real_type(item));
+  if (Field::result_merge_type(fld_type) == STRING_RESULT)
   {
     const char *old_cs, *old_derivation;
-    if (use_expression_type || !item_is_a_field)
-      field_example= 0;
-    else
-    {
-      /*
-        It is safe to assign a pointer to field here, because it will be used
-        before any table is closed.
-      */
-      field_example= field;
-    }
-
     old_cs= collation.collation->name;
     old_derivation= collation.derivation_name();
-    if (item_type == STRING_RESULT && collation.aggregate(item->collation))
+    if (collation.aggregate(item->collation))
     {
       my_error(ER_CANT_AGGREGATE_2COLLATIONS, MYF(0),
 	       old_cs, old_derivation,
 	       item->collation.collation->name,
 	       item->collation.derivation_name(),
 	       "UNION");
-      return 1;
+      return TRUE;
+    }
   }
-
-    max_length= max(max_length, new_length);
   decimals= max(decimals, item->decimals);
   maybe_null|= item->maybe_null;
-    item_type= new_result_type;
+  get_full_info(item);
-  }
+  return FALSE;
-  DBUG_ASSERT(item_type != ROW_RESULT);
-  return 0;
 }
 
+/*
+  Calculate lenth for merging result for given Item type
 
-uint32 Item_type_holder::real_length(Item *item)
+  SYNOPSIS
+    Item_type_holder::real_length()
+    item  Item for lrngth detection
+
+  RETURN
+    length
+*/
+
+uint32 Item_type_holder::display_length(Item *item)
 {
   if (item->type() == Item::FIELD_ITEM)
     return ((Item_field *)item)->max_disp_length();
 
-  switch (item->result_type())
+  switch (item->field_type())
   {
-  case STRING_RESULT:
+  case MYSQL_TYPE_DECIMAL:
+  case MYSQL_TYPE_TIMESTAMP:
+  case MYSQL_TYPE_DATE:
+  case MYSQL_TYPE_TIME:
+  case MYSQL_TYPE_DATETIME:
+  case MYSQL_TYPE_YEAR:
+  case MYSQL_TYPE_NEWDATE:
+  case MYSQL_TYPE_ENUM:
+  case MYSQL_TYPE_SET:
+  case MYSQL_TYPE_TINY_BLOB:
+  case MYSQL_TYPE_MEDIUM_BLOB:
+  case MYSQL_TYPE_LONG_BLOB:
+  case MYSQL_TYPE_BLOB:
+  case MYSQL_TYPE_VAR_STRING:
+  case MYSQL_TYPE_STRING:
+  case MYSQL_TYPE_GEOMETRY:
     return item->max_length;
-  case REAL_RESULT:
+  case MYSQL_TYPE_TINY:
+    return 4;
+  case MYSQL_TYPE_SHORT:
+    return 6;
+  case MYSQL_TYPE_LONG:
+    return 11;
+  case MYSQL_TYPE_FLOAT:
+    return 25;
+  case MYSQL_TYPE_DOUBLE:
     return 53;
-  case INT_RESULT:
+  case MYSQL_TYPE_NULL:
+    return 4;
+  case MYSQL_TYPE_LONGLONG:
     return 20;
-  case ROW_RESULT:
+  case MYSQL_TYPE_INT24:
+    return 8;
   default:
     DBUG_ASSERT(0); // we should never go there
     return 0;
   }
 }
 
+
+/*
+  Make temporary table field according collected information about type
+  of UNION result
+
+  SYNOPSIS
+    Item_type_holder::make_field_by_type()
+    table  temporary table for which we create fields
+
+  RETURN
+    created field
+*/
+
+Field *Item_type_holder::make_field_by_type(TABLE *table)
+{
+  if (fld_type == MYSQL_TYPE_ENUM || fld_type == MYSQL_TYPE_SET)
+  {
+    DBUG_ASSERT(enum_set_typelib);
+    /*
+      The field functions defines a field to be not null if null_ptr is not 0
+    */
+    uchar *null_ptr= maybe_null ? (uchar*) "" : 0;
+
+    if (fld_type == MYSQL_TYPE_ENUM)
+      return new Field_enum((char *) 0, max_length, null_ptr, 0,
+		 Field::NONE, name,
+		 table, get_enum_pack_length(enum_set_typelib->count),
+		 enum_set_typelib, collation.collation);
+    else
+      return new Field_set((char *) 0, max_length, null_ptr, 0,
+		 Field::NONE, name,
+		 table, get_set_pack_length(enum_set_typelib->count),
+		 enum_set_typelib, collation.collation);
+  }
+  return tmp_table_field_from_field_type(table);
+}
+
+
+/*
+  Get full information from Item about enum/set fields to be able to create
+  them later
+
+  SYNOPSIS
+    Item_type_holder::get_full_info
+    item    Item for information collection
+*/
+void Item_type_holder::get_full_info(Item *item)
+{
+  if (fld_type == MYSQL_TYPE_ENUM ||
+      fld_type == MYSQL_TYPE_SET)
+  {
+    /*
+      We can have enum/set type after merging only if we have one enum/set
+      field and number of NULL fields
+    */
+    DBUG_ASSERT((enum_set_typelib &&
+                 get_real_type(item) == MYSQL_TYPE_NULL) ||
+                (!enum_set_typelib &&
+                 item->type() == Item::FIELD_ITEM &&
+                 (get_real_type(item) == MYSQL_TYPE_ENUM ||
+                  get_real_type(item) == MYSQL_TYPE_SET) &&
+                 ((Field_enum*)((Item_field *) item)->field)->typelib));
+    if (!enum_set_typelib)
+    {
+      enum_set_typelib= ((Field_enum*)((Item_field *) item)->field)->typelib;
+    }
+  }
+}
+
+
 double Item_type_holder::val()
 {
   DBUG_ASSERT(0); // should never be called

sql/item.h

@@ -1321,32 +1321,32 @@ public:
 
 
 /*
-  Used to store type. name, length of Item for UNIONS & derived table
+  Item_type_holder used to store type. name, length of Item for UNIONS &
+  derived tables.
+
+  Item_type_holder do not need cleanup() because its time of live limited by
+  single SP/PS execution.
 */
 class Item_type_holder: public Item
 {
 protected:
-  Item_result item_type;
+  TYPELIB *enum_set_typelib;
-  Item_result orig_type;
+  enum_field_types fld_type;
-  Field *field_example;
-public:
-  Item_type_holder(THD*, Item*, TABLE *);
 
-  Item_result result_type () const { return item_type; }
+  void get_full_info(Item *item);
+public:
+  Item_type_holder(THD*, Item*);
+
+  Item_result result_type() const;
+  virtual enum_field_types field_type() const { return fld_type; };
   enum Type type() const { return TYPE_HOLDER; }
   double val();
   longlong val_int();
   String *val_str(String*);
-  bool join_types(THD *thd, Item *, TABLE *);
+  bool join_types(THD *thd, Item *);
-  Field *example() { return field_example; }
+  Field *make_field_by_type(TABLE *table);
-  static uint32 real_length(Item *item);
+  static uint32 display_length(Item *item);
-  void cleanup()
+  static enum_field_types get_real_type(Item *);
-  {
-    DBUG_ENTER("Item_type_holder::cleanup");
-    Item::cleanup();
-    item_type= orig_type;
-    DBUG_VOID_RETURN;
-  }
 };
 
 

sql/item_func.h

@@ -51,7 +51,7 @@ public:
 		  SP_CONTAINS_FUNC,SP_OVERLAPS_FUNC,
 		  SP_STARTPOINT,SP_ENDPOINT,SP_EXTERIORRING,
 		  SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
-		  NOT_FUNC, NOT_ALL_FUNC, NOW_FUNC};
+		  NOT_FUNC, NOT_ALL_FUNC, NOW_FUNC, VAR_VALUE_FUNC};
   enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL };
   enum Type type() const { return FUNC_ITEM; }
   virtual enum Functype functype() const   { return UNKNOWN_FUNC; }
@@ -980,6 +980,7 @@ public:
     select @t1:=1,@t1,@t:="hello",@t from foo where (@t1:= t2.b)
   */
   enum_field_types field_type() const  { return MYSQL_TYPE_STRING; }
+  enum Functype functype() const   { return VAR_VALUE_FUNC; }
   const char *func_name() const { return "get_user_var"; }
   bool const_item() const;
   table_map used_tables() const

sql/item_subselect.cc

@@ -1235,7 +1235,7 @@ int subselect_single_select_engine::prepare()
 
 int subselect_union_engine::prepare()
 {
-  return unit->prepare(thd, result, SELECT_NO_UNLOCK);
+  return unit->prepare(thd, result, SELECT_NO_UNLOCK, "");
 }
 
 int subselect_uniquesubquery_engine::prepare()

sql/sql_derived.cc

@@ -123,7 +123,7 @@ static int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit,
     DBUG_RETURN(1); // out of memory
 
   // st_select_lex_unit::prepare correctly work for single select
-  if ((res= unit->prepare(thd, derived_result, 0)))
+  if ((res= unit->prepare(thd, derived_result, 0, org_table_list->alias)))
     goto exit;
 
 	
@@ -161,7 +161,7 @@ static int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit,
     if (is_union)
     {
       // execute union without clean up
-      if (!(res= unit->prepare(thd, derived_result, SELECT_NO_UNLOCK)))
+      if (!(res= unit->prepare(thd, derived_result, SELECT_NO_UNLOCK, "")))
 	res= unit->exec();
     }
     else

sql/sql_lex.h

@@ -389,7 +389,8 @@ public:
   void exclude_tree();
 
   /* UNION methods */
-  int prepare(THD *thd, select_result *result, ulong additional_options);
+  int prepare(THD *thd, select_result *result, ulong additional_options,
+              const char *tmp_table_alias);
   int exec();
   int cleanup();
   inline void unclean() { cleaned= 0; }

sql/sql_parse.cc

@@ -4539,9 +4539,7 @@ bool add_field_to_list(THD *thd, char *field_name, enum_field_types type,
         net_printf(thd,ER_TOO_BIG_SET,field_name); /* purecov: inspected */
         DBUG_RETURN(1);				/* purecov: inspected */
       }
-      new_field->pack_length= (interval_list->elements + 7) / 8;
+      new_field->pack_length= get_set_pack_length(interval_list->elements);
-      if (new_field->pack_length > 4)
-        new_field->pack_length=8;
 
       List_iterator<String> it(*interval_list);
       String *tmp;
@@ -4558,7 +4556,7 @@ bool add_field_to_list(THD *thd, char *field_name, enum_field_types type,
   case FIELD_TYPE_ENUM:
     {
       // Should be safe
-      new_field->pack_length= interval_list->elements < 256 ? 1 : 2; 
+      new_field->pack_length= get_enum_pack_length(interval_list->elements);
 
       List_iterator<String> it(*interval_list);
       String *tmp;

sql/sql_prepare.cc

@@ -1079,7 +1079,7 @@ static int mysql_test_select(Prepared_statement *stmt,
   thd->used_tables= 0;                        // Updated by setup_fields
 
   // JOIN::prepare calls
-  if (unit->prepare(thd, 0, 0))
+  if (unit->prepare(thd, 0, 0, ""))
   {
     send_error(thd);
     goto err_prep;
@@ -1228,7 +1228,7 @@ static int select_like_statement_test(Prepared_statement *stmt,
   thd->used_tables= 0;                        // Updated by setup_fields
 
   // JOIN::prepare calls
-  if (lex->unit.prepare(thd, 0, 0))
+  if (lex->unit.prepare(thd, 0, 0, ""))
   {
     res= thd->net.report_error ? -1 : 1;
   }

sql/sql_select.cc

@@ -4836,14 +4836,7 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
     return create_tmp_field_from_item(thd, item, table, copy_func, modify_item,
                                       convert_blob_length);
   case Item::TYPE_HOLDER:
-  {
+    return ((Item_type_holder *)item)->make_field_by_type(table);
-    Field *example= ((Item_type_holder *)item)->example();
-    if (example)
-      return create_tmp_field_from_field(thd, example, item, table, 0,
-                                         convert_blob_length);
-    return create_tmp_field_from_item(thd, item, table, copy_func, 0,
-                                      convert_blob_length);
-  }
   default:					// Dosen't have to be stored
     return 0;
   }
@@ -5340,8 +5333,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     if (create_myisam_tmp_table(table,param,select_options))
       goto err;
   }
-  /* Set table_name for easier debugging */
-  table->table_name= base_name(tmpname);
   if (!open_tmp_table(table))
     DBUG_RETURN(table);
 
@@ -9525,7 +9516,8 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
     unit->fake_select_lex->select_number= UINT_MAX; // jost for initialization
     unit->fake_select_lex->type= "UNION RESULT";
     unit->fake_select_lex->options|= SELECT_DESCRIBE;
-    if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK | SELECT_DESCRIBE)))
+    if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK | SELECT_DESCRIBE,
+                             "")))
       res= unit->exec();
     res|= unit->cleanup();
   }

sql/sql_union.cc

@@ -29,7 +29,7 @@ int mysql_union(THD *thd, LEX *lex, select_result *result,
 {
   DBUG_ENTER("mysql_union");
   int res= 0;
-  if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK)))
+  if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK, "")))
     res= unit->exec();
   res|= unit->cleanup();
   DBUG_RETURN(res);
@@ -142,7 +142,8 @@ st_select_lex_unit::init_prepare_fake_select_lex(THD *thd)
 
 
 int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
-				ulong additional_options)
+				ulong additional_options,
+                                const char *tmp_table_alias)
 {
   SELECT_LEX *lex_select_save= thd_arg->lex->current_select;
   SELECT_LEX *sl, *first_select;
@@ -252,7 +253,7 @@ int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       while ((item_tmp= it++))
       {
 	/* Error's in 'new' will be detected after loop */
-	types.push_back(new Item_type_holder(thd_arg, item_tmp, empty_table));
+	types.push_back(new Item_type_holder(thd_arg, item_tmp));
       }
 
       if (thd_arg->is_fatal_error)
@@ -271,8 +272,7 @@ int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       Item *type, *item_tmp;
       while ((type= tp++, item_tmp= it++))
       {
-        if (((Item_type_holder*)type)->join_types(thd_arg, item_tmp,
+        if (((Item_type_holder*)type)->join_types(thd_arg, item_tmp))
-                                                  empty_table))
 	  DBUG_RETURN(-1);
       }
     }
@@ -304,7 +304,7 @@ int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
 				  (first_select_in_union()->options |
 				   thd_arg->options |
 				   TMP_TABLE_ALL_COLUMNS),
-				  HA_POS_ERROR, (char*) "")))
+				  HA_POS_ERROR, (char *) tmp_table_alias)))
       goto err;
     table->file->extra(HA_EXTRA_WRITE_CACHE);
     table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);