Re: libpq compression

On 22.06.2018 19:05, Nico Williams wrote:
> On Fri, Jun 22, 2018 at 10:18:12AM +0300, Konstantin Knizhnik wrote:
>> On 22.06.2018 00:34, Nico Williams wrote:
>>> So I think you just have to have lengths.
>>>
>>> Now, this being about compression, I understand that you might now want
>>> to have 4-byte lengths, especially given that most messages will be
>>> under 8KB. So use a varint encoding for the lengths.
>> No explicit framing and lengths are needed in case of using streaming
>> compression.
>> There can be certainly some kind of frames inside compression protocol
>> itself, but it is intrinsic of compression algorithm.
> I don't think that's generally true. It may be true of the compression
> algorithm you're working with. This is fine, of course, but plugging in
> other compression algorithms will require the authors to add framing.

If compression algorithm supports streaming mode (and most of them
does), then you should not worry about frames.
And if compression algorithm doesn't support streaming mode, then it
should not be used for libpq traffic compression.

--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company