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Re: COMMIT NOWAIT Performance Option

From: "J(dot) Andrew Rogers" <jrogers(at)neopolitan(dot)com>
To: "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: COMMIT NOWAIT Performance Option
Date: 2007-03-01 02:22:58
Message-ID: 98A04B82-95A4-44C7-BED3-64F5F1DB2E6E@neopolitan.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Feb 28, 2007, at 4:40 PM, Jonah H. Harris wrote:
> Oracle, Microsoft, IBM, Sybase, Teradata, MySQL, and Firebird have a
> clever feature called page checksumming which I think we should copy
> because it's simple and effective at detecting page-level corruption
> due to torn pages and/or faulty storage hardware.


Any system that does enough I/O will occasionally generate corrupted  
pages in the complete absence of any other detectable fault or  
hardware failure.  A fair amount has been written about it with  
respect to large-scale computing and it happens often enough when  
systems start getting large that just about everyone implements  
software I/O checksumming eventually to deal with the problem.  I  
simply assumed that PostgreSQL was doing the same since it is  
definitely used for systems that are large enough that this becomes a  
statistically significant issue.

A popular alternative to CRC32 for this purpose is the significantly  
cheaper and almost as effective is the Adler32 algorithm.  I know  
Google used this algorithm when they added checksumming to their  
database to tame inexplicable transient corruption.

Cheers,

J. Andrew Rogers


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