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Re: [GENERAL] Undetected corruption of table files

From: Jan Wieck <JanWieck(at)Yahoo(dot)com>
To: Albe Laurenz <all(at)adv(dot)magwien(dot)gv(dot)at>
Cc: Tom Lane *EXTERN* <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [GENERAL] Undetected corruption of table files
Date: 2007-08-31 12:08:43
Message-ID: 46D804CB.5020807@Yahoo.com (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-hackers
On 8/28/2007 4:14 AM, Albe Laurenz wrote:
> Not all databases are on enterprise scale storage systems, and
> there's also the small possibility of PostgreSQL bugs that could
> be detected that way.

Computing a checksum just before writing the block will NOT detect any 
faulty memory or Postgres bug that corrupted the block. You will have a 
perfectly fine checksum over the corrupted data.

A checksum only detects corruptions that happen between write and read. 
Most data corruptions that happen during that time however lead to some 
sort of read error reported by the disk.


Jan

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