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Re: Enabling Checksums

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>, Andres Freund <andres@2ndquadrant.com>, Simon Riggs <simon@2ndQuadrant.com>, Ants Aasma <ants@cybertec.at>, Greg Smith <greg@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2013-04-13T13:14:26Z
Lists: pgsql-hackers 
On Fri, Apr 12, 2013 at 02:38:27PM -0700, Jeff Davis wrote:
> In general, we have more flexibility with WAL because there is no
> upgrade issue. It would be nice to share code with the data page
> checksum algorithm; but really we should just use whatever offers the
> best trade-off in terms of complexity, performance, and error detection
> rate.
> 
> I don't think we need to decide all of this right now. Personally, I'm
> satisfied having SIMD checksums on data pages now and leaving WAL
> optimization until later.

As I understand it, SIMD is just a CPU-optimized method for producing a
CRC checksum.  Is that right?  Does it produce the same result as a
non-CPU-optimized CRC calculation?

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +