added collation processing in UNION merging

temporary table BLOB now is longblob


mysql-test/r/create.result:
  blob size changed for safety
mysql-test/r/type_blob.result:
  blob size changed for safety
mysql-test/r/type_ranges.result:
  blob size changed for safety
mysql-test/r/union.result:
  blob size changed for safety
  new tests of UNION types merging
mysql-test/t/union.test:
  new tests of UNION types merging
sql/field.h:
  blob size changed for safety
sql/item.cc:
  processing of collation added
  added comment
sql/item.h:
  joining of UNION fields may failed now, because of incompatibility of collations
sql/sql_union.cc:
  joining of UNION fields may failed now, because of incompatibility of collations

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index e2c90e4ff4c..44a30082c0a 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -197,7 +197,8 @@ int st_select_lex_unit::prepare(THD *thd, select_result *sel_result)
       Item *type, *item;
       while((type= tp++, item= it++))
       {
-	((Item_type_holder*)type)->join_types(thd, item);
+	if (((Item_type_holder*)type)->join_types(thd, item))
+	  DBUG_RETURN(-1)
       }
     }
   }