From: pgsql-hackers-owner@postgresql.org
> [mailto:pgsql-hackers-owner@postgresql.org] On Behalf Of Amit Kapila
> > I think the reason why increasing shared_buffers didn't give better
> performance for read-only tests than you expect is that the relation files
> are cached in the filesystem cache. The purpose of this verification is
> to know that the effective upper limit is not 512MB (which is too small
> now), and I think the purpose is achieved. There may be another threshold,
> say 32GB or 128GB, over which the performance degrades due to PostgreSQL
> implementation, but that's another topic which also applies to other OSes.
> >
>
> If we don't get any benefit by increasing the shared_buffers on windows,
> then what advantage do you see in recommending higher value?
No, I'm not recommending a higher value, but just removing the doubtful sentences of 512MB upper limit. The advantage
isthat eliminating this sentence will make a chance for users to try best setting.
> I generally run it for 20 to 30 mins for read-write tests. Also, to ensure
> consistent data, please consider changing following parameters in
> postgresql.conf checkpoint_timeout = 35 minutes or so, min_wal_size = 5GB
> or so, max_wal_size = 20GB or so and checkpoint_completion_target=0.9.
>
> Apart from above, ensure to run manual checkpoint (checkpoint command) after
> each test.
Thank you, I'll try the read-write test with these settings on the weekend, when my PC is available. I understood that
yourintention is to avoid being affected by checkpointing and WAL segment creation.
Regards
Takayuki Tsunakawa