From: Scott Ribe <scott_ribe@elevated-dev.com>
To: Ron <ronljohnsonjr@gmail.com>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: pg_dump -Z6 (the default) can be pretty slow
Date: Wed, 18 Oct 2023 16:37:22 -0600
Message-ID: <E9615CEC-CB92-4825-8BFC-0099F90107BD@elevated-dev.com> (raw)
In-Reply-To: <c2157b92-8802-41c9-a6b8-435d6d3793c0@gmail.com>
References: <c2157b92-8802-41c9-a6b8-435d6d3793c0@gmail.com>
If you can use the directory format, then you can use multiple jobs to really speed up compressed dump (and restore).
Also, I'd suggest trying a run with lz4 compression--lz4 is particularly good at not slowing down when it encounters already-compressed data. Doesn't give really high compression ratios, but since you're already at -Z3, might be worth comparing.
(Personally, I stay away from zstd, as I've seen it create malformed backups because the encoder crashes with out-of-memory.)
--
Scott Ribe
scott_ribe@elevated-dev.com
https://www.linkedin.com/in/scottribe/> On Oct 18, 2023, at 4:30 PM, Ron <ronljohnsonjr@gmail.com> wrote:
>
> In preparation for moving from 9.6 to something supported, I ran a pg_dump/pg_restore test (since the migrated databases will be on new servers, and we purge off old partitions and add new partitions, pg_upgrade and logical replication are off the table).
>
> (The servers are VMs on ESX hosts, and on the same subnet.)
>
> Our databases are chock full of bytea fields holding compressed images. pg_dump -Fd -Z6 took 25 minutes, and 5.5GB disk space. (remember, it's a test!), while pg_dump -Fd -Z0 only took 90 seconds, but consumed 15GB.
>
> This isn't really surprising to anyone who's ever tried to gzip a jpg file...
>
> Quite the speed increase if you can swallow the increased disk usage.
>
> pg_dump -Z3 did the best: only 8.5 minutes, while using just 5.8GB disk space.
>
> --
> Born in Arizona, moved to Babylonia.
>
>
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To: pgsql-admin@postgresql.org
Cc: scott_ribe@elevated-dev.com, ronljohnsonjr@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: pg_dump -Z6 (the default) can be pretty slow
In-Reply-To: <E9615CEC-CB92-4825-8BFC-0099F90107BD@elevated-dev.com>
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