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MDEV-16357 LIMIT and ORDER BY clause is ignored on a query with UNION

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when using brackets

Do not create master unit for select if it has already one.
This commit is contained in:
Igor Babaev
2018-11-06 09:40:07 -08:00
parent 074c684099
commit 41e68e8e5b
3 changed files with 45 additions and 0 deletions
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24
mysql-test/main/brackets.result
View File

@ -219,4 +219,28 @@ select 1 union select 1 union select 1;
((select 1) union (select 1) union (select 1));
1
1
#
# MDEV-16357: union in brackets with tail
# union with tail in brackets
#
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES(1),(2),(3),(4);
CREATE TABLE t2 (a int);
INSERT INTO t2 VALUES (4),(5),(6),(7);
(SELECT a FROM t1 UNION SELECT a FROM t2) LIMIT 1;
a
1
(SELECT a FROM t1 UNION SELECT a FROM t2) ORDER BY a DESC;
a
7
6
5
4
3
2
1
(SELECT a FROM t1 UNION SELECT a FROM t2 LIMIT 1);
a
1
DROP TABLE t1,t2;
# End of 10.4 tests

18
mysql-test/main/brackets.test
View File

@ -88,5 +88,23 @@ select 1 union select 1 union select 1;
(select 1 union select 1 union select 1);
((select 1) union (select 1) union (select 1));
--echo #
--echo # MDEV-16357: union in brackets with tail
--echo # union with tail in brackets
--echo #
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES(1),(2),(3),(4);
CREATE TABLE t2 (a int);
INSERT INTO t2 VALUES (4),(5),(6),(7);
(SELECT a FROM t1 UNION SELECT a FROM t2) LIMIT 1;
(SELECT a FROM t1 UNION SELECT a FROM t2) ORDER BY a DESC;
(SELECT a FROM t1 UNION SELECT a FROM t2 LIMIT 1);
DROP TABLE t1,t2;
--echo # End of 10.4 tests

3
sql/sql_lex.cc
View File

@ -5250,6 +5250,9 @@ LEX::create_unit(SELECT_LEX *first_sel)
SELECT_LEX_UNIT *unit;
DBUG_ENTER("LEX::create_unit");
if (first_sel->master_unit())
DBUG_RETURN(first_sel->master_unit());
if (!(unit= alloc_unit()))
DBUG_RETURN(NULL);