Re: [PATCH] pg_stat_toast

From: "Gunnar \"Nick\" Bluth" <gunnar(dot)bluth(at)pro-open(dot)de>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "kuroda(dot)hayato(at)fujitsu(dot)com" <kuroda(dot)hayato(at)fujitsu(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>
Subject: Re: [PATCH] pg_stat_toast
Date: 2022-04-06 16:20:29
Message-ID: a93d920c-ae8d-76a9-319e-4fda2d76ca38@pro-open.de
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Am 06.04.22 um 17:49 schrieb Robert Haas:

> I feel like if you want to know whether externalization made a
> difference, you can look at the size of the TOAST table. And by
> selecting directly from that table, you can even see how many chunks
> it contains, and how many are full-sized chunks vs. partial chunks,
> and stuff like that. And for compression, how about looking at
> pg_column_size(col1) vs. pg_column_size(col1||'') or something like
> that? You might get a 1-byte varlena header on the former and a 4-byte
> varlena header on the latter even if there's no compression, but any
> gains beyond 3 bytes have to be due to compression.

I'll probably give that a shot!

It does feel a bit like noting your mileage on fuel receipts though, as
I've done until I got my first decent car; works and will work perfectly
well up to the day, but certainly is a bit out-of-time (and requires
some basic math skills ;-).

Best,
--
Gunnar "Nick" Bluth

Eimermacherweg 106
D-48159 Münster

Mobil +49 172 8853339
Email: gunnar(dot)bluth(at)pro-open(dot)de
__________________________________________________________________________
"Ceterum censeo SystemD esse delendam" - Cato

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