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From: Laurenz Albe <[email protected]>
To: Christophe Pettus <[email protected]>
To: bruno vieira da silva <[email protected]>
Cc: [email protected]
Subject: Re: data checksums
Date: Wed, 07 Aug 2024 04:45:44 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAB+Nuk8y88kvoRHsfN2Pjed9o_iM+9FbveU=4P8G0EQbzFP+qw@mail.gmail.com>
	<[email protected]>

On Tue, 2024-08-06 at 09:29 -0700, Christophe Pettus wrote:
> 
> > On Aug 6, 2024, at 08:11, bruno vieira da silva <[email protected]> wrote:
> > 
> > so my question is why data checksums aren't enabled by default on pg?
> 
> At this point, mostly historical reasons.  They're also superfluous if your underlying
> file system or storage hardware does storage-level corruption checks (which most don't).

I am surprised by that.  Would you say that most storage systems will happily give you a
garbage block if there was a hardware problem somewhere?

> > the pg doc 
> > mentions a considerable performance penality, how considerable it is?
> 
> That line is probably somewhat out of date at this point.  We haven't seen a significant
> slowdown in enabling them on any modern hardware.  I always turn them on, except on the
> type of filesystems/hardware mentioned above.

Turning data checksums on will write WAL for hint bits, which can significantly increase
the amount of WAL written.

Yours,
Laurenz Albe

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