On 3 January 2017 at 21:33, Robert Haas <robertmh...@gmail.com> wrote: > On Tue, Jan 3, 2017 at 3:38 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >> On 3 January 2017 at 16:24, Robert Haas <robertmh...@gmail.com> wrote: >>> On Jan 3, 2017 at 11:16 AM, Simon Riggs <si...@2ndquadrant.com> wrote: >>>> On 3 January 2017 at 15:44, Robert Haas <robertmh...@gmail.com> wrote: >>>>> Yeah. I don't think there's any way to get around the fact that there >>>>> will be bigger latency spikes in some cases with larger WAL files. >>>> >>>> One way would be for the WALwriter to zerofill new files ahead of >>>> time, thus avoiding the latency spike. >>> >>> Sure, we could do that. I think it's an independent improvement, >>> though: it is beneficial with or without this patch. >> >> The latency spike problem is exacerbated by increasing file size, so I >> think if we are allowing people to increase file size in this release >> then we should fix the knock-on problem it causes in this release >> also. If we don't fix it as part of this patch I would consider it an >> open item. > > I think I'd like to see some benchmark results before forming an > opinion on whether that's a must-fix issue. I'm not sure I believe > that allowing a larger WAL segment size is going to make things worse > more than it makes them better. I think that should be tested, not > assumed true.
Strange response. Nothing has been assumed. I asked for tests and you provided measurements. I suggest we fix just the problem as the fastest way forwards. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers