On Thu, May 17, 2018 at 3:54 AM, Konstantin Knizhnik
<k.knizhnik@postgrespro.ru> wrote:
> 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.
Speaking of configuration, are you planning to support multiple
compression libraries at the same time? It looks like the current
patch implicitly requires client and server to use the same configure
option, without any attempt to detect or negotiate. Do I guess
correctly that a library mismatch would produce an incomprehensible
corrupt stream message?
--
Thomas Munro
http://www.enterprisedb.com