On Mon, 2011-01-31 at 13:55 -0600, Kevin Grittner wrote: > Jeff Davis <pg...@j-davis.com> wrote: > > > I don't think this function really cares about the visibility with > > respect to the current snapshot, right? > > What it cares about is whether some other particular top level > transaction wrote a tuple which we *would* read except that it is > not visible to us because that other top level transaction is > concurrent with ours.
Or a tuple that you *are* reading, but is being deleted concurrently, right? Or has been deleted by an overlapping transaction? > If so, we want to flag a read-write conflict > out from our transaction and in to that other transaction. It still seems like HTSV would suffice, unless I'm missing something. I think "visible" is still needed though: it matters in the cases HEAPTUPLE_RECENTLY_DEAD and HEAPTUPLE_LIVE. For the former, it only allows an early exit (if !visible); but for the latter, I think it's required. Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers