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In-Reply-To: <5c4b2864-3baf-4ebc-8405-280fc1a1c8a9@iki.fi>
From: Maxim Orlov <orlovmg@gmail.com>
Date: Thu, 4 Dec 2025 13:03:23 +0300
Message-ID: 
 <CACG=ezZHPFN2qdPAACDOpYmExUP_tujO2QbirqUB7jRWp+ADmA@mail.gmail.com>
Subject: Re: POC: make mxidoff 64 bits
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Alexander Korotkov <aekorotkov@gmail.com>,
 Alvaro Herrera <alvherre@alvh.no-ip.org>,
	wenhui qiu <qiuwenhuifx@gmail.com>,
	Postgres hackers <pgsql-hackers@lists.postgresql.org>,
	Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
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On Wed, 3 Dec 2025 at 15:04, Heikki Linnakangas <hlinnaka@iki.fi> wrote:

>
> There are plenty of such critical bytes in the system where a single bit
> flip renders the whole block unreadable. Actually, if we had checksums
> on SLRU pages, a single bit flip anywhere in the page would make the
> checksum fail and render the block unreadable.
>
> Correct. However, my concern about the lack of checksums for SLRU wasn't
about data loss and the impossibility of recovering it, but about the
impossibility of detecting the error.  But it is how it is for now.

-- 
Best regards,
Maxim Orlov.

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote g=
mail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, 3 Dec 2=
025 at 15:04, Heikki Linnakangas &lt;<a href=3D"mailto:hlinnaka@iki.fi">hli=
nnaka@iki.fi</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" styl=
e=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);paddin=
g-left:1ex"><br>
There are plenty of such critical bytes in the system where a single bit <b=
r>
flip renders the whole block unreadable. Actually, if we had checksums <br>
on SLRU pages, a single bit flip anywhere in the page would make the <br>
checksum fail and render the block unreadable.<br><br></blockquote><div>Cor=
rect. However, my concern about the lack of checksums for SLRU wasn&#39;t<b=
r>about data loss and the impossibility of recovering it, but about the<br>=
impossibility of detecting the error.=C2=A0 But it is how it is for now.</d=
iv></div><div><br clear=3D"all"></div><span class=3D"gmail_signature_prefix=
">-- </span><br><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr"=
><div>Best regards,<br></div><div>Maxim Orlov.</div></div></div></div>

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