On Tue, Nov 15, 2016 at 7:14 AM, Tsunakawa, Takayuki
<tsunakawa.ta...@jp.fujitsu.com> wrote:
> From: pgsql-hackers-ow...@postgresql.org
>> [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Amit Kapila
>> Okay, not a problem.  However, I am not sure the results in this thread
>> are sufficient proof as for read-only tests, there is no noticeable win
>> by increasing shared buffers and read-write tests seems to be quite short
>> (60 seconds) to rely on it.
> 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?

> How about 3 minutes for read-write tests?  How long do you typically run?

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.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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