Re: [GENERAL] 8.1.4 - problem with PITR - .backup.done /

On Tue, 2006-05-30 at 09:45 -0400, Tom Lane wrote:
> "Rafael Martinez, Guerrero" <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no> writes:
> > The problem was that 000000010000000800000010.0006D5E8.backup was
> > already archived, but under pg_xlog/archive_status/ there were two
> > files:
> > -------------------------------------------------
> > 000000010000000800000010.0006D5E8.backup.done
> > 000000010000000800000010.0006D5E8.backup.ready
> > -------------------------------------------------
>
> > This situation should not happen, anyone has seen this problem before?
>
> No, it shouldn't. What I suspect is that XLogArchiveIsDone() got
> confused and created a duplicate .ready file. It basically assumes
> that the only way its stat() calls can fail is ENOENT, ie, file not
> there ... but I wonder if they failed for some other reason instead.
> What sort of platform and filesystem is this on?
>

This is on a AMD64 Opteron server with RHELAS4 / 2.6.9-34.ELsmp and ext3
filesystem. This is the first time this happens.

I cannot the postgres internals but after a quick look to the source
code ......

XLogArchiveIsDone() has this code in the final of the function:
-------------------------------------------------
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;

/* Retry creation of the .ready file */
XLogArchiveNotify(xlog);
return false;
}
-------------------------------------------------

What happens if we have a race condition and the archiver creates
a .done file between the last check for the .done file and the creation
of the .ready file by XLogArchiveNotify?

> Did you happen to make note of the mod times of the two files before
> deleting them?
>

No, I did not :( If it happens again, I will do.

regards,
--
Rafael Martinez, <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no>
Center for Information Technology Services
University of Oslo, Norway

PGP Public Key: http://folk.uio.no/rafael/