UNION does not respect ORDER BY or LIMIT

[VinaiRachakonda]

Consider the following setup:

DROP TABLE IF EXISTS `c_file`;
CREATE TABLE `c_file` (
  `filename` varchar(255) NOT NULL,
  `data` text NOT NULL,
  `timestamp` bigint NOT NULL,
  PRIMARY KEY (`filename`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `c_file` (`filename`,`data`,`timestamp`) VALUES ('huey.txt','huey task queue',1515225600);
INSERT INTO `c_file` (`filename`,`data`,`timestamp`) VALUES ('peewee.txt','peewee orm',1515052800);
INSERT INTO `c_file` (`filename`,`data`,`timestamp`) VALUES ('walrus.txt','walrus redis toolkit',1515139200);
DROP TABLE IF EXISTS `c_note`;
CREATE TABLE `c_note` (
  `id` int NOT NULL AUTO_INCREMENT,
  `content` text NOT NULL,
  `timestamp` bigint NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `c_note` (`id`,`content`,`timestamp`) VALUES (1,'note-a',1514793600);
INSERT INTO `c_note` (`id`,`content`,`timestamp`) VALUES (2,'note-b',1514880000);
INSERT INTO `c_note` (`id`,`content`,`timestamp`) VALUES (3,'note-c',1514966400);

Consider the following query

 (SELECT `t1`.`content`, `t1`.`timestamp` FROM `c_note` AS `t1`) UNION (SELECT `t2`.`filename`, `t2`.`timestamp` FROM `c_file` AS `t2`) ORDER BY timestamp DESC LIMIT 4;

Dolt incorrectly returns

+------------+------------+
| content    | timestamp  |
+------------+------------+
| note-a     | 1514793600 |
| note-b     | 1514880000 |
| note-c     | 1514966400 |
| huey.txt   | 1515225600 |
| peewee.txt | 1515052800 |
| walrus.txt | 1515139200 |
+------------+------------+

Mysql correctly returns

+------------+------------+
| content    | timestamp  |
+------------+------------+
| huey.txt   | 1515225600 |
| walrus.txt | 1515139200 |
| peewee.txt | 1515052800 |
| note-c     | 1514966400 |
+------------+------------+

[VinaiRachakonda]

This currently blocks the Peewee ORM

[VinaiRachakonda]

Skipped enginetest here

[reltuk]

Going to iterate here: dolthub/go-mysql-server#1169

[timsehn]

Looks like @reltuk fixed this and did not resolve.