Message-ID: <27eb89fc-8fdd-2988-0959-0af1d6d7a12a@enterprisedb.com>
Date: Mon, 3 Apr 2023 23:26:09 +0200
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Subject: Re: zstd compression for pg_dump
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To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Jacob Champion <jchampion@timescale.com>, pgsql-hackers@postgresql.org,
 gkokolatos@pm.me, Michael Paquier <michael@paquier.xyz>,
 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>
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
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On 4/3/23 21:17, Justin Pryzby wrote:
> On Sat, Apr 01, 2023 at 10:26:01PM +0200, Tomas Vondra wrote:
>>> Feel free to mess around with threads (but I'd much rather see the patch
>>> progress for zstd:long).
>>
>> OK, understood. The long mode patch is pretty simple. IIUC it does not
>> change the format, i.e. in the worst case we could leave it for PG17
>> too. Correct?
> 
> Right, libzstd only has one "format", which is the same as what's used
> by the commandline tool.  zstd:long doesn't change the format of the
> output: the library just uses a larger memory buffer to allow better
> compression.  There's no format change for zstd:workers, either.
> 

OK. I plan to do a bit more review/testing on this, and get it committed
over the next day or two, likely including the long mode. One thing I
noticed today is that maybe long_distance should be a bool, not int.
Yes, ZSTD_c_enableLongDistanceMatching() accepts int, but it'd be
cleaner to cast the value during a call and keep it bool otherwise.

regards

-- 
Tomas Vondra
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