From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin@lists.postgresql.org
Subject: Precompressed data in TOASTed columns (was Re: Regarding postgreSQL performance on DRAM)
Date: Wed, 20 Feb 2019 18:38:20 -0600
Message-ID: <d01fb828-72cb-83ea-d69a-62f80cb4dc6d@gmail.com> (raw)
In-Reply-To: <29251.1550696663@sss.pgh.pa.us>
References: <CADb0YNk+jYXt6oC3vefFzOigmG8WOCkXmeAq5L8ABA4eMbypHA@mail.gmail.com>
<87va1exlfo.fsf@jsievers.enova.com>
<f37b7ea7-966d-d54a-bf8d-a1c7229e5f8a@gmx.net>
<29251.1550696663@sss.pgh.pa.us>
On 2/20/19 3:04 PM, Tom Lane wrote:
[snip]
> Well, the entire tuple would be 25600 bytes plus some overhead, which
> cannot fit on a Postgres page (8K, unless the OP changed compile options
> without mentioning it). So something has to be done to make it fit, and
> that something is going to be toasting any fields that can be toasted.
>
> From memory, our threshold for trying to make tuples narrower is only
> a quarter-page anyway, so that the toaster will be trying to get this
> down to 2K if it can. That's certainly going to involve compressing
> every field, and I wouldn't be surprised if a lot of them get shoved
> out-of-line too.
>
> The OP might care to read
>
> https://www.postgresql.org/docs/current/storage-toast.html
Based on that and https://www.postgresql.org/docs/9.6/sql-altertable.html
should I think about doing a SET STORAGE=EXTERNAL on columns with PDF and
compressed TIFF data?
Thanks
--
Angular momentum makes the world go 'round.
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To: pgsql-admin@postgresql.org
Cc: ronljohnsonjr@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: Precompressed data in TOASTed columns (was Re: Regarding postgreSQL performance on DRAM)
In-Reply-To: <d01fb828-72cb-83ea-d69a-62f80cb4dc6d@gmail.com>
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