Re: libpq compression

> 26 марта 2019 г., в 19:46, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> написал(а):
>
> Version of the patch correctly working when no compression algorithm are avaiable.

Thanks for this work, Konstantin.
PFA rebased version of this patch.

This compression seems very important to reduce network-induced replication lag.
Recently I've found out that small installation suffer from huge latency spike when archive_timeout occurs.
How this happens? archive_timeout emits segment switch, which pads current segment with zeroes. Now these zeroes need to be replicated to standbys, without compression. Transfer of zeroes causes long waits for synchronous replication (up to 1s with network restricted to 16Mbps).

Also replication compression will reduce overall cross-AZ traffic of HA installations.

So I'm considering following plan for 2020: implement this protocol in Odyssey and send patches to drivers to enable early access to this feature.

Best regards, Andrey Borodin.