From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Jeff Frost <jeff@frostconsultingllc.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Richard Huxton <dev@archonet.com>
Cc: pgsql-docs@postgresql.org
Subject: Re: Proposed doc-patch: Identifying the Current WAL file
Date: Sat, 15 Apr 2006 14:42:31 -0400 (EDT)
Message-ID: <200604151842.k3FIgVm10059@candle.pha.pa.us> (raw)
In-Reply-To: <Pine.LNX.4.64.0604151119520.9581@discord.dyndns.org>
Jeff Frost wrote:
> On Sat, 15 Apr 2006, Bruce Momjian wrote:
>
> > Tom Lane wrote:
> >
> > No, I am not:
> >
> > $ touch x1 x2; touch x2
> > $ sleep 2; ls -lt
> > total 0
> > -rw-r--r-- 1 root postgres 0 Apr 15 14:04 x1
> > -rw-r--r-- 1 root postgres 0 Apr 15 14:04 x2
> >
> > If the write to x2 happens in the first second, but no later writes
> > happen, you still see x1 as first, even though x2 is the new one and
> > might have WAL data in it. The point is that the test does not have a
> > one-second window of showing the wrong answer, meaning I could wait for
> > 60 seconds, and still see the wrong WAL file at the top.
>
> Bruce, what does
>
> stat x1 x2
>
> look like on your system? Which OS? Maybe we need caveats for various OSes?
System is BSD/OS:
$ touch x1 x2; stat x1 x2
filename: x1
inode: 4547362
device: 18,7
size: 0
type: regular file
links: 1
mode: 0644(-rw-r--r--)
owner: 0(root)
group: 102(postgres)
access: Sat Apr 15 14:41:12 2006
modification: Sat Apr 15 14:41:12 2006
change: Sat Apr 15 14:41:12 2006
filename: x2
inode: 4547363
device: 18,7
size: 0
type: regular file
links: 1
mode: 0644(-rw-r--r--)
owner: 0(root)
group: 102(postgres)
access: Sat Apr 15 14:41:12 2006
modification: Sat Apr 15 14:41:12 2006
change: Sat Apr 15 14:41:12 2006
And I tried it on Fedora Core 2:
bmomjian@x86-linux2:~$ touch x1 x2 ; stat x1 x2
File: `x1'
Size: 0 Blocks: 0 IO Block: 8192 regular
empty file
Device: 11h/17d Inode: 24707337 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 7078/bmomjian) Gid: ( 100/ users)
Access: 2006-04-15 11:41:53.000000000 -0700
Modify: 2006-04-15 11:41:53.000000000 -0700
Change: 2006-04-15 11:41:53.000000000 -0700
File: `x2'
Size: 0 Blocks: 0 IO Block: 8192 regular
empty file
Device: 11h/17d Inode: 24707338 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 7078/bmomjian) Gid: ( 100/ users)
Access: 2006-04-15 11:41:53.000000000 -0700
Modify: 2006-04-15 11:41:53.000000000 -0700
Change: 2006-04-15 11:41:53.000000000 -0700
--
Bruce Momjian http://candle.pha.pa.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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To: pgsql-docs@postgresql.org
Cc: pgman@candle.pha.pa.us, jeff@frostconsultingllc.com, tgl@sss.pgh.pa.us, dev@archonet.com
Subject: Re: Proposed doc-patch: Identifying the Current WAL file
In-Reply-To: <200604151842.k3FIgVm10059@candle.pha.pa.us>
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