Cascade-save breaks if parent ID is assigned (delays insert) and child has identity ID (early insert) (Wallace Wadge)

(reposting here from forum)

Consider:

• a table with an assigned PK (i.e. not auto-increment), let's call this "A"

• Another table ("B") linked to the table listed above but with it's PK set to auto-increment.

Now if you try to save B with cascading switched on, it will break. From the little debugging I've done it looks like:

a) hibernate detects that A needs to be saved first, but puts it into some sort of queue.
b) when it hits B, it short-circuits this save queue and tries to save B immediately so as to obtain a PK reference for B. This fails since A hasn't been yet been saved so it's link is still null.

Schema used is listed below (MySQL):

CREATE DATABASE `jira` /*!40100 DEFAULT CHARACTER SET latin1 */;

DROP TABLE IF EXISTS `jira`.`parent`;
CREATE TABLE `jira`.`parent` (
`parent_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`parent_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

DROP TABLE IF EXISTS `jira`.`child`;
CREATE TABLE `jira`.`child` (
`child_id` int(10) unsigned NOT NULL auto_increment,
`parent_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`child_id`),
KEY `FK_child_1` (`parent_id`),
CONSTRAINT `FK_child_1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`parent_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;