| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Enabling Checksums |
| Date: | 2013-03-06 08:41:07 |
| Message-ID: | CA+U5nML8pZyg=EVWMd_b7-JZ52fU7HKOA5s6Lo3YSnLa_Jim+w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 5 March 2013 18:02, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
> Fletcher is probably significantly faster than CRC-16, because I'm just
> doing int32 addition in a tight loop.
>
> Simon originally chose Fletcher, so perhaps he has more to say.
IIRC the research showed Fletcher was significantly faster for only a
small loss in error detection rate.
It was sufficient to make our error detection > 1 million times
better, possibly more. That seems sufficient to enable early detection
of problems, since if we missed the first error, a second is very
likely to be caught (etc). So I am assuming that we're trying to catch
a pattern of errors early, rather than guarantee we can catch the very
first error.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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