Date: Fri, 24 Feb 2023 22:50:41 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-hackers@postgresql.org, gkokolatos@pm.me,
	Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Robert Haas <robertmhaas@gmail.com>, Peter Geoghegan <pg@bowt.ie>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
	Heikki Linnakangas <hlinnaka@iki.fi>,
	Thomas Munro <thomas.munro@gmail.com>,
	Dipesh Pandit <dipesh.pandit@gmail.com>,
	Andrey Borodin <x4mmm@yandex-team.ru>,
	Mark Dilger <mark.dilger@enterprisedb.com>
Subject: Re: zstd compression for pg_dump
Message-ID: <20230225045041.GG1653@telsasoft.com>
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On Sat, Feb 25, 2023 at 01:44:36PM +0900, Michael Paquier wrote:
> On Fri, Feb 24, 2023 at 01:18:40PM -0600, Justin Pryzby wrote:
> > This is a draft patch - review is welcome and would help to get this
> > ready to be considererd for v16, if desired.
> > 
> > I'm going to add this thread to the old CF entry.
> > https://commitfest.postgresql.org/31/2888/
> 
> Patch 0003 adds support for the --long option of zstd, meaning that it
> "enables long distance matching with #windowLog".  What's the benefit
> of that when it is applied to dumps and base backup contents?

It (can) makes it smaller.

+           The <literal>long</literal> keyword enables long-distance matching
+           mode, for improved compression ratio, at the expense of higher memory
+           use.  Long-distance mode is supported only for 

+        With zstd compression, <literal>long</literal> mode may allow dumps
+        to be significantly smaller, but it might not reduce the size of
+        custom or directory format dumps, whose fields are separately compressed.

Note that I included that here as 003, but I also have an pre-existing
patch for adding that just to basebackup.

-- 
Justin