Description:
EXPLAIN can show the following in the "extra" column
unique row not found
but this is not documented in the manual
How to repeat:
CREATE TABLE `BB` (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`int_key` int(11) DEFAULT NULL,
PRIMARY KEY (`pk`),
KEY `int_key` (`int_key`),
KEY `varchar_key` (`int_key`)
) ENGINE=InnoDB AUTO_INCREMENT=29 DEFAULT CHARSET=latin1;
INSERT INTO `BB` VALUES (5,NULL),(6,NULL),(22,NULL),(23,NULL),(24,NULL),(27,NULL),(28,NULL),(25,0),(11,9);
CREATE TABLE `DD` (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`int_key` int(11) DEFAULT NULL,
PRIMARY KEY (`pk`),
KEY `int_key` (`int_key`),
KEY `varchar_key` (`int_key`)
) ENGINE=InnoDB AUTO_INCREMENT=138 DEFAULT CHARSET=latin1;
INSERT INTO `DD` VALUES (18,NULL),(30,NULL),(34,NULL),(46,NULL),(55,NULL),(58,NULL),(59,NULL),(63,NULL),(73,NULL),(76,NULL),(89,NULL),(90,NULL),(97,NULL),(105,NULL),(110,NULL),(111,NULL),(112,NULL),(114,NULL),(123,NULL),(124,NULL),(125,NULL),(126,NULL),(127,NULL),(130,NULL),(131,NULL),(133,NULL),(134,NULL),(135,NULL),(136,NULL),(80,1),(26,2),(50,2),(43,3),(83,3),(92,3),(95,3),(96,3),(44,4),(51,4),(54,4),(57,4),(67,4),(68,4),(94,4),(99,4),(109,4),(27,5),(35,5),(38,5),(41,5),(42,5),(49,5),(56,5),(64,5),(66,5),(82,5),(86,5),(88,5),(108,5),(47,6),(52,6),(98,6),(107,6),(20,7),(24,7),(32,7),(39,7),(40,7),(61,7),(69,7),(81,7),(84,7),(87,7),(137,7),(70,8),(77,8),(91,8),(101,8),(103,8),(23,9),(25,9),(28,9),(29,9),(31,9),(33,9),(36,9),(37,9),(48,9),(62,9),(72,9),(74,9),(75,9),(93,9),(106,9),(19,42),(100,58),(104,78),(102,80),(45,135),(53,169),(65,198);
EXPLAIN SELECT X . `int_key`
FROM `DD` AS X LEFT JOIN `BB` AS Y USING ( `pk` )
WHERE X . `pk` = 125
LIMIT 8 ;
