On Mon, Nov 12, 2012 at 11:20 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Fri, Nov 9, 2012 at 3:31 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >>> So what we're talking about here is a new mode for COPY, that when >>> requested will pre-freeze tuples when loading into a newly >>> created/truncated table. If the table isn't newly created/truncated >>> then we'll just ignore it and continue. I see no need to throw an >>> error, since that will just cause annoying usability issues. > >> Actually, why not just have it work always? If people want to load >> frozen tuples into a table that's not newly created/truncated, why not >> let them? Sure, there could be MVCC violations, but as long as the >> behavior is opt-in, who cares? I think it'd be useful to a lot of >> people. > > I thought about that too, but there's a big problem. It wouldn't be > just MVCC that would be broken, but transactional integrity: if the > COPY fails partway through, the already-loaded rows still look valid. > The new-file requirement provides a way to roll them back. > > I'm willing to have an option that compromises MVCC semantics > transiently, but giving up transactional integrity seems a bit much.
Hmm, good point. There might be some way around that, but figuring it out is probably material for a separate patch. But I guess that raises the question - should COPY (FREEZE) silently ignore the option for not-new relfilenodes, or should it error out? Simon proposed the former, but I'm wondering if the latter would be better. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
