On Wed, Jan 4, 2017 at 9:47 AM, Simon Riggs <si...@2ndquadrant.com> wrote: > On 4 January 2017 at 13:57, Robert Haas <robertmh...@gmail.com> wrote: >> On Wed, Jan 4, 2017 at 3:05 AM, Simon Riggs <si...@2ndquadrant.com> wrote: >>> Strange response. Nothing has been assumed. I asked for tests and you >>> provided measurements. >> >> Sure, of zero-filling a file with dd. But I also pointed out that in >> a real PostgreSQL cluster, the change could actually *reduce* latency. > > I think we are talking at cross purposes. We agree that the main > change is useful, but it causes another problem which I can't see how > you can characterize as reduced latency, based upon your own > measurements.
Zero-filling files will take longer if the files are bigger. That will increase latency. But we will also have fewer forced end-of-segment syncs. That will reduce latency. Which effect is bigger? -- 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
