1berry/MariaDB-server
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Bug #27786:

Browse Source 
When merging views into the enclosing statement
the ORDER BY clause of the view is merged to the
parent's ORDER BY clause.
However when the VIEW is merged into an UNION
branch the ORDER BY should be ignored. 
Use of ORDER BY for individual SELECT statements
implies nothing about the order in which the rows
appear in the final result because UNION by default
produces unordered set of rows.
Fixed by ignoring the ORDER BY clause from the merge
view when expanded in an UNION branch.
This commit is contained in:
gkodinov/kgeorge@magare.gmz 2007-04-20 10:49:45 +03:00
parent 6ad81b4e13
commit 4c89a5960f
4 changed files with 66 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
mysql-test/r/view.result
View File

@ -3319,4 +3319,39 @@ lgid clid
2 YES
DROP VIEW v1;
DROP table t1,t2;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2),(3);
CREATE VIEW v1 AS SELECT a FROM t1 ORDER BY a;
SELECT * FROM t1 UNION SELECT * FROM v1;
a
1
2
3
EXPLAIN SELECT * FROM t1 UNION SELECT * FROM v1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
2 UNION t1 ALL NULL NULL NULL NULL 3
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
SELECT * FROM v1 UNION SELECT * FROM t1;
a
1
2
3
EXPLAIN SELECT * FROM v1 UNION SELECT * FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
2 UNION t1 ALL NULL NULL NULL NULL 3
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
SELECT * FROM t1 UNION SELECT * FROM v1 ORDER BY a;
a
1
2
3
EXPLAIN SELECT * FROM t1 UNION SELECT * FROM v1 ORDER BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
2 UNION t1 ALL NULL NULL NULL NULL 3
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL Using filesort
DROP VIEW v1;
DROP TABLE t1;
End of 5.0 tests.

16
mysql-test/t/view.test
View File

@ -3205,4 +3205,20 @@ SELECT * FROM v1;
DROP VIEW v1;
DROP table t1,t2;
#
# Bug#27786: Inconsistent Operation Performing UNION On View With ORDER BY
#
CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (1),(2),(3);
CREATE VIEW v1 AS SELECT a FROM t1 ORDER BY a;
SELECT * FROM t1 UNION SELECT * FROM v1;
EXPLAIN SELECT * FROM t1 UNION SELECT * FROM v1;
SELECT * FROM v1 UNION SELECT * FROM t1;
EXPLAIN SELECT * FROM v1 UNION SELECT * FROM t1;
SELECT * FROM t1 UNION SELECT * FROM v1 ORDER BY a;
EXPLAIN SELECT * FROM t1 UNION SELECT * FROM v1 ORDER BY a;
DROP VIEW v1;
DROP TABLE t1;
--echo End of 5.0 tests.

8
sql/sql_lex.h
View File

@ -468,6 +468,7 @@ public:
bool change_result(select_subselect *result, select_subselect *old_result);
void set_limit(st_select_lex *values);
void set_thd(THD *thd_arg) { thd= thd_arg; }
inline bool is_union ();
friend void lex_start(THD *thd, uchar *buf, uint length);
friend int subselect_union_engine::exec();
@ -700,6 +701,13 @@ public:
};
typedef class st_select_lex SELECT_LEX;
inline bool st_select_lex_unit::is_union ()
{
return first_select()->next_select() &&
first_select()->next_select()->linkage == UNION_TYPE;
}
#define ALTER_ADD_COLUMN 1
#define ALTER_DROP_COLUMN 2
#define ALTER_CHANGE_COLUMN 4

9
sql/sql_view.cc
View File

@ -1263,13 +1263,18 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
unit->slave= save_slave; // fix include_down initialisation
}
/*
We can safely ignore the VIEW's ORDER BY if we merge into union
branch, as order is not important there.
*/
if (!table->select_lex->master_unit()->is_union())
table->select_lex->order_list.push_back(&lex->select_lex.order_list);
/*
This SELECT_LEX will be linked in global SELECT_LEX list
to make it processed by mysql_handle_derived(),
but it will not be included to SELECT_LEX tree, because it
will not be executed
*/
table->select_lex->order_list.push_back(&lex->select_lex.order_list);
*/
goto ok;
}