On Feb 18, 2008 9:42 AM, Tom Hughes <[EMAIL PROTECTED]> wrote: > That still has race conditions unless you can do the check in an > atomic fashion, which I'm not sure you can.
It can work: For inserting/updating ways you're checking the nodes exist already, add a FOR SHARE to each query This stops someone else deleting them in the meantime. And a FOR UPDATE on the way against concurrent updates. For deleting a node, in the initial existance check add a FOR UPDATE to the query. Now check the ways/relations (nothing special needed here). Finally delete the node. It's poor man's referential integrity, but it's what Real Databases do in the background when doing referential integrity. > Well obviously we could just lock everything, but the users of > the API probably wouldn't like the result much. AFAICS it doesn't require any additional queries so the performance effect should be marginal. But it probably only works for innodb tables :( Have a nice day, -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
