Simon Riggs <[EMAIL PROTECTED]> writes: > On Mon, 2007-11-19 at 10:38 -0500, Tom Lane wrote: >> The race conditions are a lot more subtle than that. The stats >> collector cannot know when it receives a tabstat message after VACUUM >> starts whether VACUUM has/will see the tuples involved, or whether it >> will see them as committed or not. That would depend on whether VACUUM >> has yet reached the page(s) the tuples are in.
> I think the before-and-after approach can be made to work: > VACUUM just needs to save the counter in memory, it doesn't need to > write that anywhere else. > VACUUM can force the flush of the tabstat file so that there is no race > condition, or at least a minimised one. I don't think you understood what I said at all. The race condition is not "before vs after VACUUM starts", it is "before vs after when VACUUM scans the page that the in-doubt tuple is in". regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly