Re: libpq compression

From: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
To: Grigory Smolkin <g(dot)smolkin(at)postgrespro(dot)ru>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: libpq compression
Date: 2018-05-16 15:54:13
Message-ID: 429cf55b-a8bf-c4ba-196d-5b45420145a1@postgrespro.ru
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On 16.05.2018 18:09, Grigory Smolkin wrote:
>
> Hello!
> I have noticed that psql --help lack -Z|--compression option.
> Also it would be nice to have option like --compression-level in psql
> and pgbench.
>
Thank you for this notice.
Updated and rebased patch is attached.
Concerning specification of compression level: I have made many
experiments with different data sets and both zlib/zstd and in both
cases using compression level higher than default doesn't cause some
noticeable increase of compression ratio, but quite significantly reduce
speed. Moreover, for "pgbench -i" zstd provides better compression ratio
(63 times!) with compression level 1 than with with largest recommended
compression level 22! This is why I decided not to allow user to choose
compression level.

Attachment Content-Type Size
libpq-compression-3.patch text/x-patch 35.2 KB

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