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. -- 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