Re: Loading the latest N rows into the cache seems way too fast.

From: Ron Johnson <ronljohnsonjr(at)gmail(dot)com>
To: pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: Loading the latest N rows into the cache seems way too fast.
Date: 2025-02-17 23:03:18
Message-ID: CANzqJaC=6pUTsveOdL=FS1vz_FGjMbZKuzJ27JxsPfNbYN2fUA@mail.gmail.com
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On Mon, Feb 17, 2025 at 4:51 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Ron Johnson <ronljohnsonjr(at)gmail(dot)com> writes:
> > On Mon, Feb 17, 2025 at 4:36 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> It's not pulling in the TOAST storage where the bytea column lives.
> >> (pg_prewarm wouldn't have either, without special pushups.)
>
> > Puzzling, since I ran "PERFORM *". What if I explicitly mentioned the
> > bytea column's name?
>
> You'd have to do something that actually used the column's value,
> perhaps "md5(byteacol)" or such. (The obvious candidate would be
> length(), but I think that is optimized to not fetch or decompress
> the whole value.)
>

That's definitely taking a LOT longer...

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