On 2016-04-13 13:52:15 -0500, Kevin Grittner wrote: > On Wed, Apr 13, 2016 at 12:25 PM, Robert Haas <robertmh...@gmail.com> wrote: > > > [test results with old_snapshot_threshold = 0 and 10] > > From the docs: > > | A value of -1 disables this feature, and is the default. > > > Yuck. Aside from the fact that performance tanks when the feature is > > turned on, it seems that there is a significant effect even with it > > turned off. > > No evidence of that has been provided. -1 is off; 0 is for testing > very fast expiration.
Longer tests are running, but, again on the previous hardware with only two sockets, the results for 128 clients are: 0: progress: 100.0 s, 593351.0 tps, lat 0.215 ms stddev 0.118 progress: 200.0 s, 594035.9 tps, lat 0.215 ms stddev 0.118 progress: 300.0 s, 594013.3 tps, lat 0.215 ms stddev 0.117 -1: progress: 100.0 s, 600835.3 tps, lat 0.212 ms stddev 0.049 progress: 200.0 s, 601466.1 tps, lat 0.212 ms stddev 0.048 progress: 300.0 s, 601529.5 tps, lat 0.212 ms stddev 0.047 reverted: progress: 100.0 s, 612676.6 tps, lat 0.208 ms stddev 0.048 progress: 200.0 s, 613214.3 tps, lat 0.208 ms stddev 0.047 progress: 300.0 s, 613384.3 tps, lat 0.208 ms stddev 0.047 This is all on virtualized (though using a dedicated instance) hardware. So they numbers are to be taken with a grain of salt. But I did run shorter tests in various orders, and the runtime difference apears to be very small. - Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
