Re: Enabling Checksums

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Jeff Davis <pgsql(at)j-davis(dot)com>
Cc: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndQuadrant(dot)com>, Ants Aasma <ants(at)cybertec(dot)at>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Enabling Checksums
Date: 2013-04-13 13:14:26
Message-ID: 20130413131426.GA4604@momjian.us
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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(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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

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