On June 5, 2015 10:02:37 PM GMT+02:00, Robert Haas <robertmhaas@xxxxxxxxx> wrote: >On Fri, Jun 5, 2015 at 2:47 PM, Andres Freund <andres@xxxxxxxxxxx> >wrote: >> On 2015-06-05 14:33:12 -0400, Tom Lane wrote: >>> Robert Haas <robertmhaas@xxxxxxxxx> writes: >>> > 1. The problem that we might truncate an SLRU members page away >when >>> > it's in the buffers, but not drop it from the buffers, leading to >a >>> > failure when we try to write it later. >> >> I've got a fix for this, and about three other issues I found during >> development of the new truncation codepath. >> >> I'll commit the fix tomorrow. > >OK. Then I think we should release next week, so we get the fixes we >have out before PGCon. The current situation is not good. > >>> > I think we might want to try to fix one or both of those before >>> > cutting a new release. I'm less sold on the idea of installing >>> > WAL-logging in this minor release. That probably needs to be >done, >>> > but right now we've got stuff that worked in early 9.3.X release >and >>> > is now broken, and I'm in favor of fixing that first. >> >> I've implemented this, and so far it removes more code than it >> adds. It's imo also a pretty clear win in how understandable the code >> is. The remaining work, besides testing, is primarily going over >lots >> of comment and updating them. Some of them are outdated by the patch, >> and some already were. >> >> Will post tonight, together with the other fixes, after I get back >from >> climbing. >> >> My gut feeling right now is that it's a significant improvement, and >> that it'll be reasonable to include it. But I'd definitely like some >> independent testing for it, and I'm not sure if that's doable in time >> for the wrap. > >I think we would be foolish to rush that part into the tree. We >probably got here in the first place by rushing the last round of >fixes too much; let's try not to double down on that mistake. My problem with that approach is that I think the code has gotten significantly more complex in the least few weeks. I have very little trust that the interactions between vacuum, the deferred truncations in the checkpointer, the state management in shared memory and recovery are correct. There's just too many non-local subtleties here. I don't know what the right thing to do here is. --- Please excuse brevity and formatting - I am writing this on my mobile phone. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
