Re: pglz performance

Hi,

On 2019-08-02 19:00:39 +0200, Tomas Vondra wrote:
> On Fri, Aug 02, 2019 at 09:39:48AM -0700, Andres Freund wrote:
> > Hi,
> >
> > On 2019-08-02 20:40:51 +0500, Andrey Borodin wrote:
> > > We have some kind of "roadmap" of "extensible pglz". We plan to
> > > provide implementation on Novembers CF.
> >
> > I don't understand why it's a good idea to improve the compression side
> > of pglz. There's plenty other people that spent a lot of time
> > developing better compression algorithms.
> >
>
> Isn't it beneficial for existing systems, that will be stuck with pglz
> even if we end up adding other algorithms?

Why would they be stuck continuing to *compress* with pglz? As we
fully retoast on write anyway we can just gradually switch over to the
better algorithm. Decompression speed is another story, of course.

Here's what I had a few years back:

https://www.postgresql.org/message-id/20130621000900.GA12425%40alap2.anarazel.de
see also
https://www.postgresql.org/message-id/20130605150144.GD28067%40alap2.anarazel.de

I think we should refresh something like that patch, and:
- make the compression algorithm GUC an enum, rename
- add --with-system-lz4
- obviously refresh the copy of lz4
- drop snappy

Greetings,

Andres Freund