Re: [HACKERS] [COMMITTERS] pgsql: Revert "commit_delay" change; just add comment that we don't hav
Peter Geoghegan writes: > I'm not quite comfortable recommending a switch to milliseconds if > that implies a loss of sub-millisecond granularity. I know that > someone is going to point out that in some particularly benchmark, > they can get another relatively modest increase in throughput (perhaps > 2%-3%) by splitting the difference between two adjoining millisecond > integer values. In that scenario, I'd be tempted to point out that > that increase is quite unlikely to carry over to real-world benefits, > because the setting is then right on the cusp of where increasing > commit_delay stops helping throughput and starts hurting it. The > improvement is likely to get lost in the noise in the context of a > real-world application, where for example the actually cost of an > fsync is more variable. I'm just not sure that that's the right > attitude. To me it's more about future-proofing. commit_delay is the only time-interval setting we've got where reasonable values today are in the single-digit-millisecond range. So it seems to me not hard to infer that in a few years sub-millisecond values will be important, whether or not there's any real argument for them today. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] [COMMITTERS] pgsql: Revert "commit_delay" change; just add comment that we don't hav
Peter Geoghegan writes: > Why does commit_delay have to be an integer? Can't we devise a way of > manipulating it in units of milliseconds, but have the internal > representation be a double, as with pg_stat_statements' total_time > column? If you wanted to re-implement all the guc.c logic for supporting unit-ified values such that it would also work with floats, we could do that. It seems like way more mechanism than the problem is worth however. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] [COMMITTERS] pgsql: Revert "commit_delay" change; just add comment that we don't hav
Peter Geoghegan writes: > On 14 August 2012 21:26, Bruce Momjian wrote: >> Revert "commit_delay" change; just add comment that we don't have >> a microsecond specification. > I think that if we eventually decide to change the name of > commit_delay for 9.3 (you previously suggested that that might be > revisited), it will be reasonable to have the new GUC in units of > milliseconds. Well, the reason why it's like that at all is the thought that values of less than 1 millisecond might be useful. Are we prepared to suppose that that is not and never will be true? regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
