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 21:48:56
Message-ID:
87k602v4xj.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:
> I think short burst errors are fairly likely: the kind of scenario I'm
> worried about is a wild store corrupting a word of a WAL entry while
> it's waiting around to be written in the WAL buffers.
Ah, does this mean that each WAL entry gets its own checksum? In this
case, Adler32 is indeed suboptimal because it doesn't use the full 32
bits for short inputs. It might still catch many wild stores, but the
statistics are worse than for CRC32.
(I had assumed that PostgreSQLs WAL checksumming was justified by the
partial write issue. The wild store could easily occur with a heap
page, too, and AFAIK, tuples, aren't checksummed. Which would be an
interesting option, I guess.)
In response to
Responses
pgsql-hackers by date
Next :From: Tom LaneDate: 2007-01-04 22:03:45Subject : Re: [HACKERS] wal_checksum = on (default) | off Previous :From : Simon RiggsDate : 2007-01-04 21:48:36Subject : Re: Tabs or Spaces
pgsql-patches by date
Next :From: Tom LaneDate: 2007-01-04 22:03:45Subject : Re: [HACKERS] wal_checksum = on (default) | off Previous :From : Gurjeet SinghDate : 2007-01-04 20:26:12Subject : Re: [HACKERS] [Fwd: Index Advisor]
