----- On 10 Apr, 2019, at 10:23 AM, Andres Freund andres@xxxxxxxxxxx wrote: > On 2019-04-09 17:12:27 -0500, Justin Pryzby wrote: >> You could test that's the issue by comparing with fsync=off (please read what >> that means and don't run your production cluster like that). >> https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-FSYNC > > I suggest testing it with synchronous_commit=off instead. That's about > as fast for this type of workload, doesn't have cluster corruption > issues, the window of a transaction not persisting in case of a crash is > very small, and it can just set by any user in individual sessions. Bingo! Adding 'SET LOCAL synchronous_commit TO OFF;' to my 'BEGIN; UPDATE ....; COMMIT;' block has given me sub-1ms timings! Thanks Andres. I'll probably leave the setting as that on my local machine. The option appears to be relatively safe, but my machine is just a dev test machine anyway. Regards, Duncan Kinnear
