"Matt Clark" <[EMAIL PROTECTED]> writes: > OK I'm definitely missing something here.
The point is that a big seqscan (either VACUUM or a plain table scan) hits a lot of pages, and thereby tends to fill your cache with pages that aren't actually likely to get hit again soon, perhaps pushing out pages that will be needed again soon. This happens at both the shared-buffer and kernel-disk-cache levels of caching. It would be good to find some way to prevent big seqscans from populating cache, but I don't know of any portable way to tell the OS that we don't want it to cache a page we are reading. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster