Simon Riggs <si...@2ndquadrant.com> writes: > On Fri, 2011-01-21 at 11:19 +0200, Heikki Linnakangas wrote: >> It's not the order in which the xid was assigned that matters, but the >> order the transactions started and got their snapshots. The xids might >> be assigned a lot later, after the transactions have already read data.
> So if a read-write transaction assigns an xid before it takes a snapshot > then we'll be OK? That seems much easier to arrange than passing chunks > of snapshot data backwards and forwards. Optionally. No, that idea is DOA from a performance standpoint. We sweated blood to avoid having to assign XIDs to read-only transactions, and we're not going back. If SSI requires that, SSI is not getting committed. 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