On Mon, Dec 1, 2008 at 6:09 PM, Joachim Zobel <[EMAIL PROTECTED]> wrote: > Am Mittwoch, den 26.11.2008, 12:54 +0000 schrieb Matt Amos: >> > Well, as long as the API code is good, and makes this check, then >> the >> > transaction should cover it for inserts/updates. I'd assume the >> > migration script will have to handle existing inconsistencies. >> >> that is exactly why i'm worrying about it :-) > > MySQL has the > > SET foreign_key_checks = 0; > > which can be set before loading the old data. The somewhat scary fact > that a > > SET foreign_key_checks = 1; > > does _not_ do a validation of the existing data means that handling > existing inconsistencies can be delayed until the migration is done.
this is, indeed, a very scary feature of mysql. even within a transaction on an innodb table it will still check foreign key constraints as the rows are added - mysql has no concept of "deferred constraints" like most other databases. while writing the migration script i'm having to run with the foreign key checks on to ensure that i have covered all the "existing inconsistencies", which makes it really slow :-) but don't worry - once the script works we can turn checks off and everything will work perfectly, of course. :-P cheers, matt _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
