I wrote: >> Another point that requires some thought is that switching SnapshotNow >> to be MVCC-based will presumably result in a noticeable increase in each >> backend's rate of wanting to acquire snapshots.
BTW, I wonder if this couldn't be ameliorated by establishing some ground rules about how up-to-date a snapshot really needs to be. Arguably, it should be okay for successive SnapshotNow scans to use the same snapshot as long as we have not acquired a new lock in between. If not, reusing an old snap doesn't introduce any race condition that wasn't there already. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers