From: | Francisco Olarte <folarte(at)peoplecall(dot)com> |
---|---|
To: | Thomas Güttler <guettliml(at)thomas-guettler(dot)de> |
Cc: | "pgsql-generallists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Script which shows performance of ByteA: ascii vs binary |
Date: | 2019-03-22 17:37:12 |
Message-ID: | CA+bJJbxmcCc1dWXiaSW-8Gi_u4qKBoCo0=Y4=ii5TFUdr6hLmw@mail.gmail.com |
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Lists: | pgsql-general |
Thomas:
On Fri, Mar 22, 2019 at 2:03 PM Thomas Güttler
<guettliml(at)thomas-guettler(dot)de> wrote:
> > I'm not too sure, but I read ( in the code ) you are measuring a
> > nearly not compressible urandom data againtst a highly compressible (
...
> for this case toast-tables/wal is a detail of the implementation.
> This tests does not care about the "why it takes longer". It just generates
> a performance chart.
> Yes, it does exactly what you say: it compares
> nearly not compressible urandom data against a highly compressible data.
> In my case, will get nearly random data (binary PDF, JPG, ...). And that's why
> I wanted to benchmark it.
Well, if all you wanted is to benchmark, a performance chart, you know
it. I assumed you wanted to know more, like where the bottleneck is
and how to try to avoid it. My fault.
I was specifically confused because, IIRC, you said ascii data took
much longer than binary, which is a completely different test ( you
can test ascii vs binary by generating
chunks of random numbers in say, the 0 to 127 and sending that data
once as is and once more shifting left by one every byte. That should
test ascii-binary differences, but
if you test random vs uniform I think the problem is in the
randomness, you could just test sending '\x92'*i, or something
similar, but if you are just interested in the benchmark, you have it
done.
Just one thing, a single graph with two labels "ascii" and "random" is
misleading, as constant/random is orthogonal with ascii/binary, but as
I said, my fault, all the text about psycopg and other stuff led me to
think you wanted some kind of diagnosis and improvements.
Regards.
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