Re: Question about wal_compression and what to expect

Yes, my question was essentially do I need to separately compress WAL
files for storage/archiving even with wal_compression set. So, I think
you've answered my question.

Thanks!
Sean

On June 20, 2023, "Wetmore, Matthew (CTR)" <matthew(dot)wetmore(at)express-
scripts.com> wrote:
> From my understanding,
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> Wal_compression will compress full page writes in the wal file.  The
> size of your wal is configurable.
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> So for your 16MB wal, it’s already compressed into the wal, and your
> wal_size won’t change.  (just more data can fit into your 16MB)
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> As far as archiving, I create a dir, then tar.gz the dir for storage.
> (if that was your question)
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> From: Sean O'Grady <sean(at)thingee(dot)com>
> Sent: Tuesday, June 20, 2023 11:19 AM
> To: pgsql-admin(at)lists(dot)postgresql(dot)org
> Subject: [EXTERNAL] Question about wal_compression and what to expect
>
>  
>
> Hello,
>
> I've enabled wal_compression however I do not see any change in the
> 16MB size for each WAL file. Through all my googling and searching the
> mailing lists, I could not find a description if a change *should* be
> expected even though many of the articles I've read indicate
> compression can save disk space. 
>
> I am currently thinking that the records in the WAL file are
> compressed for the purpose of writing less data to disk, but that the
> file is still padded to 16MB. If so, does that mean to realize a space
> savings for archiving that my archive_command should compress the file
> (gzip, bz2, etc)?
>
> Thanks,
> Sean O'Grady
>