Re: Proposal: Integrity check - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Proposal: Integrity check
Date
Msg-id 3479.1201287276@sss.pgh.pa.us
Whole thread Raw
In response to Re: Proposal: Integrity check  (Zdenek Kotala <Zdenek.Kotala@Sun.COM>)
Responses Re: Proposal: Integrity check  ("Zeugswetter Andreas ADI SD" <Andreas.Zeugswetter@s-itsolutions.at>)
Re: Proposal: Integrity check  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-hackers
Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
> Tom Lane wrote:
>> This seems like a pretty horrid idea.  Bad pages shouldn't be allowed to
>> get into shared buffers in the first place.  Why not have the checking
>> logic operate outside shared buffers?

> It currently works outside the shared buffers, but I afraid about 
> collision due to parallel read and write access on one block. I'm not 
> sure if parallel write(8k) and read(8k) is synchronized by kernel/fs or 
> not. If not it should generates false positive results. If yes than I'm 
> happy :-) with outside processing.

We're already assuming that; otherwise base backups for PITR don't work.
        regards, tom lane


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