On Wed, Jul 27, 2016 at 11:01 AM, Adrian Klaver <adrian.kla...@aklaver.com> wrote:
> On 07/27/2016 07:52 AM, thomas veymont wrote: > >> >> 2016-07-27 14:11 GMT+02:00 Michael Paquier <michael.paqu...@gmail.com >> <mailto:michael.paqu...@gmail.com>>: >> >> >> >> >> And do you see changes if you increase min_wal_size? This will >> increase the number of WAL segments recycled instead of removed at >> each checkpoint. >> -- >> Michael >> >> >> I have seen no improvment with the following parameters in 9.5: >> max_wal_size = 3GB >> min_wal_size = 512MB >> #checkpoint_completion_target = 0.5 # checkpoint target duration, >> 0.0 - 1.0 >> #checkpoint_warning = 30s # 0 disables >> >> while my 9.3 configuration is: >> checkpoint_segments = 128 # in logfile segments, min 1, >> 16MB each >> #checkpoint_timeout = 5min # range 30s-1h >> checkpoint_completion_target = 0.9 # checkpoint target duration, >> 0.0 - 1.0 >> #checkpoint_warning = 30s # 0 disables >> >> I have just run a quick pgbench test to get some objective numbers. >> Both tests were run on the same machine (ie. production machine), same >> disk, same logical volume : >> >> On 9.5 : >> >> $ pgbench -c 4 -j 2 -T 600 test >> starting vacuum...end. >> transaction type: TPC-B (sort of) >> scaling factor: 70 >> query mode: simple >> number of clients: 4 >> number of threads: 2 >> duration: 600 s >> number of transactions actually processed: 77318 >> latency average: 31.041 ms >> tps = 128.859708 (including connections establishing) >> tps = 128.860447 (excluding connections establishing) >> >> On 9.3 : >> >> $ pgbench -c 4 -j 2 -T 600 test >> starting vacuum...end. >> transaction type: TPC-B (sort of) >> scaling factor: 70 >> query mode: simple >> number of clients: 4 >> number of threads: 2 >> duration: 600 s >> number of transactions actually processed: 1834436 >> latency average: 1.308 ms >> tps = 3057.387254 (including connections establishing) >> tps = 3057.398493 (excluding connections establishing) >> >> Note that the 9.3 is handling others production requests in the same time. >> >> Is a checkpoint_segment/WAL problem still to be suspected ? >> > > Where did you get the respective versions of Postgres? > > Where they installed the same way? > > You mentioned the log feed showing obvious performance issues, can we see > the relevant portions? > > >> cheers >> Tom >> >> > > -- > Adrian Klaver > adrian.kla...@aklaver.com > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > *I have to ask, was a vacuumdb -Z OR psql -U postgres -c ANALYZE ; * *done after the migration?* *Without accurate stats, performance goes down the drain.* -- *Melvin Davidson* I reserve the right to fantasize. Whether or not you wish to share my fantasy is entirely up to you.
