Bug#5507: TRUNCATE does not work with views.

Support of views wasn't implemented for the TRUNCATE statement.
Now TRUNCATE on views has the same semantics as DELETE FROM view:
mysql_truncate() checks whether the table is a view and falls back
to delete if so.
In order to initialize properly the LEX::updatable for a view
st_lex::can_use_merged() now allows usage of merged views for the
TRUNCATE statement.

mysql-test/r/truncate.result

@@ -53,3 +53,30 @@ a
 3
 4
 drop table t1;
+create table t1 (s1 int);
+insert into t1 (s1) values (1), (2), (3), (4), (5);
+create view v1 as select * from t1;
+truncate table v1;
+select count(*) from t1;
+count(*)
+0
+insert into t1 (s1) values (1), (2), (3), (4), (5);
+create view v2 as select * from t1 where s1 > 3;
+truncate table v2;
+select * from t1;
+s1
+1
+2
+3
+select * from v2;
+s1
+delete from t1;
+create table t2 (s1 int, s2 int);
+create view v3 as select a.s1, b.s2 from t1 a join t2 b on a.s1 = b.s1 where a.s1 > 3;
+truncate table v3;
+ERROR HY000: Can not delete from join view 'test.v3'
+create view v4 as select * from t1 limit 1,1;
+truncate table v4;
+ERROR HY000: The target table v4 of the TRUNCATE is not updatable
+drop view v1, v2, v3, v4;
+drop table t1, t2;

mysql-test/r/view.result

@@ -2395,6 +2395,16 @@ Table	Op	Msg_type	Msg_text
 test.v1	optimize	error	'test.v1' is not BASE TABLE
 Warnings:
 Error	1347	'test.v1' is not BASE TABLE
+ANALYZE TABLE v1;
+Table	Op	Msg_type	Msg_text
+test.v1	analyze	error	'test.v1' is not BASE TABLE
+Warnings:
+Error	1347	'test.v1' is not BASE TABLE
+REPAIR TABLE v1;
+Table	Op	Msg_type	Msg_text
+test.v1	repair	error	'test.v1' is not BASE TABLE
+Warnings:
+Error	1347	'test.v1' is not BASE TABLE
 DROP VIEW v1;
 create definer = current_user() sql security invoker view v1 as select 1;
 show create view v1;

mysql-test/t/truncate.test

@@ -52,3 +52,35 @@ SELECT * from t1;
 drop table t1;
 
 # End of 4.1 tests
+
+# Test for Bug#5507 "TRUNCATE should work with views"
+
+create table t1 (s1 int); 
+
+insert into t1 (s1) values (1), (2), (3), (4), (5);
+create view v1 as select * from t1;
+truncate table v1;
+select count(*) from t1;
+
+insert into t1 (s1) values (1), (2), (3), (4), (5);
+create view v2 as select * from t1 where s1 > 3;
+truncate table v2; 
+select * from t1;
+select * from v2;
+delete from t1;
+
+# The following should fail
+create table t2 (s1 int, s2 int);
+create view v3 as select a.s1, b.s2 from t1 a join t2 b on a.s1 = b.s1 where a.s1 > 3;
+--error 1395
+truncate table v3; 
+
+# The following should fail
+create view v4 as select * from t1 limit 1,1; 
+--error 1288
+truncate table v4;
+
+drop view v1, v2, v3, v4;
+drop table t1, t2;
+
+# End of 5.0 tests

mysql-test/t/view.test

@@ -2228,6 +2228,8 @@ REPAIR TABLE v1;
 
 DROP TABLE t1;
 OPTIMIZE TABLE v1;
+ANALYZE TABLE v1;
+REPAIR TABLE v1;
 
 DROP VIEW v1;
 

sql/sql_delete.cc

@@ -369,6 +369,8 @@ bool mysql_prepare_delete(THD *thd, TABLE_LIST *table_list, Item **conds)
 {
   Item *fake_conds= 0;
   SELECT_LEX *select_lex= &thd->lex->select_lex;
+  const char *operation = thd->lex->sql_command == SQLCOM_TRUNCATE ?
+                          "TRUNCATE" : "DELETE";
   DBUG_ENTER("mysql_prepare_delete");
   List<Item> all_fields;
 
@@ -383,14 +385,14 @@ bool mysql_prepare_delete(THD *thd, TABLE_LIST *table_list, Item **conds)
     DBUG_RETURN(TRUE);
   if (!table_list->updatable || check_key_in_view(thd, table_list))
   {
-    my_error(ER_NON_UPDATABLE_TABLE, MYF(0), table_list->alias, "DELETE");
+    my_error(ER_NON_UPDATABLE_TABLE, MYF(0), table_list->alias, operation);
     DBUG_RETURN(TRUE);
   }
   {
     TABLE_LIST *duplicate;
     if ((duplicate= unique_table(thd, table_list, table_list->next_global, 0)))
     {
-      update_non_unique_table_error(table_list, "DELETE", duplicate);
+      update_non_unique_table_error(table_list, operation, duplicate);
       DBUG_RETURN(TRUE);
     }
   }
@@ -895,7 +897,8 @@ bool mysql_truncate(THD *thd, TABLE_LIST *table_list, bool dont_send_ok)
   if (!dont_send_ok)
   {
     db_type table_type;
-    mysql_frm_type(thd, path, &table_type);
+    if (mysql_frm_type(thd, path, &table_type) == FRMTYPE_VIEW)
+      goto trunc_by_del;
     if (table_type == DB_TYPE_UNKNOWN)
     {
       my_error(ER_NO_SUCH_TABLE, MYF(0),

sql/sql_lex.cc

@@ -1834,6 +1834,7 @@ bool st_lex::can_use_merged()
   case SQLCOM_UPDATE_MULTI:
   case SQLCOM_DELETE:
   case SQLCOM_DELETE_MULTI:
+  case SQLCOM_TRUNCATE:
   case SQLCOM_INSERT:
   case SQLCOM_INSERT_SELECT:
   case SQLCOM_REPLACE: