On Wed, Apr 22, 2009 at 5:44 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Wed, Apr 22, 2009 at 2:58 PM, Heikki Linnakangas >> <heikki.linnakan...@enterprisedb.com> wrote: >>> It still does. A prepared xact is just like a idle-in-transaction backend as >>> far as vacuum is concerned. > >> Is that really necessary? It's true that you can't vacuum away any >> rows whose xmin is that of the prepared xact, but it seems like you >> wouldn't need to keep rows just because they were *visible* to the >> prepared xact. Once prepared, it's no longer capable of reading them. > > I think we've already milked what we can from that, since a prepared > xact is treated exactly like an open one with no snapshot. The point > is that whatever rows it's written are still in-doubt and cannot be > frozen, so the wraparound horizon cannot advance past its XID.
But surely that's not "the same" as a backend which is idle-in-transaction? In that case I think you still need a snapshot? ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
