From:
Florian Weimer <fw(at)deneb(dot)enyo(dot)de>
To:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc:
"Simon Riggs" <simon(at)2ndquadrant(dot)com>,pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org
Subject:
Re: [HACKERS] wal_checksum = on (default) | off
Date:
2007-01-04 20:16:02
Message-ID:
87r6uawnst.fsf@mid.deneb.enyo.de (view raw or flat )
Thread:
2007-01-04 14:27:56 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-04 15:00:56 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 15:56:39 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-04 16:09:59 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 16:51:50 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-04 17:13:57 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 17:53:44 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-05 10:01:31 from "Zeugswetter Andreas ADI SD" <ZeugswetterA(at)spardat(dot)at>
2007-01-05 10:35:47 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-05 11:30:46 from "Zeugswetter Andreas ADI SD" <ZeugswetterA(at)spardat(dot)at>
2007-01-05 14:39:53 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-05 16:25:08 from "Zeugswetter Andreas ADI SD" <ZeugswetterA(at)spardat(dot)at>
2007-01-05 21:41:01 from Jim Nasby <decibel(at)decibel(dot)org>
2007-01-06 03:57:32 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-06 04:05:56 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2007-01-06 14:41:02 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-06 21:30:08 from Bruce Momjian <bruce(at)momjian(dot)us>
2007-01-11 04:32:51 from Bruce Momjian <bruce(at)momjian(dot)us>
2007-01-11 11:32:12 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-11 14:01:09 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-11 14:54:52 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-11 14:59:26 from Gregory Stark <stark(at)enterprisedb(dot)com>
2007-01-11 15:07:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-11 16:18:36 from Gregory Stark <stark(at)enterprisedb(dot)com>
2007-01-11 16:22:19 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-11 16:25:28 from Gregory Stark <stark(at)enterprisedb(dot)com>
2007-01-11 16:37:38 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-11 17:06:11 from Gregory Stark <stark(at)enterprisedb(dot)com>
2007-01-11 23:10:38 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-12 10:09:28 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2007-01-04 16:58:51 from Florian Weimer <fweimer(at)bfk(dot)de>
2007-01-04 17:05:04 from "Simon Riggs" <simon(at)2ndquadrant(dot)com>
2007-01-04 17:07:03 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 19:18:12 from Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>
2007-01-04 19:43:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 20:16:02 from Florian Weimer <fw(at)deneb(dot)enyo(dot)de>
2007-01-04 20:22:10 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2007-01-04 21:48:56 from Florian Weimer <fw(at)deneb(dot)enyo(dot)de>
2007-01-04 22:03:45 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Lists:
pgsql-hackers pgsql-patches
* Tom Lane:
> Florian Weimer <fweimer(at)bfk(dot)de> writes:
>> Have you tried switching to Adler32 instead of CRC32?
>
> Is anything known about the error detection capabilities of Adler32?
> There's a lot of math behind CRCs but AFAIR Adler's method is pretty
> much ad-hoc.
Correct me if I'm wrong, but the main reason for the WAL CRC is to
detect partial WAL writes (due to improper caching, for instance).
This means that you're out of the realm of traditional CRC analysis
anyway, because the things you are guarding against are neither burts
errors nor n-bit errors (for small n).
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