Re: [HACKERS] Custom compression methods

From: Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>
To: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
Cc: Ildus Kurbangaliev <i(dot)kurbangaliev(at)postgrespro(dot)ru>, Ildar Musin <i(dot)musin(at)postgrespro(dot)ru>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Евгений Шишкин <itparanoia(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Oleg Bartunov <obartunov(at)gmail(dot)com>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Chapman Flack <chap(at)anastigmatix(dot)net>
Subject: Re: [HACKERS] Custom compression methods
Date: 2018-04-24 11:05:20
Message-ID: CAPpHfduorgpFjQprDPXcUz3MYiau66z+fdrrepxhF+ZfDcy-aA@mail.gmail.com
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On Mon, Apr 23, 2018 at 7:34 PM, Konstantin Knizhnik <
k(dot)knizhnik(at)postgrespro(dot)ru> wrote:

> IMHO end-user do not have skills and time to create their own compression
> algorithms. And without knowledge of specific of particular data set,
> it is very hard to implement something more efficient than universal
> compression library.
> But if you think that it is not a right place and time to discuss it, I do
> not insist.
>

For sure, end-users wouldn't implement own compression algorithms.
In the same way as end-users wouldn't implement custom datatypes,
operator classes, procedural language handlers etc. But those are
useful extension mechanisms which pass test of time. And extension
developers use them.

> But in any case, I think that it will be useful to provide some more
> examples of custom compression API usage.
> From my point of view the most useful will be integration with zstd.
> But if it is possible to find some example of data-specific compression
> algorithms which show better results than universal compression,
> it will be even more impressive.
>

Yes, this patch definitely lacks of good usage example. That may
lead to some misunderstanding of its purpose. Good use-cases
should be shown before we can consider committing this. I think
Ildus should try to implement at least custom dictionary compression
method where dictionary is specified by user in parameters.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

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