PostgreSQL Administration - Checkpoint Location Format

Author

Checkpoint Location Format

Andy Shellam

2006-11-07, 7:18 pm

Hi,

I'm writing an automated file-system level backup application for use
with WAL archiving, that will issue the pg_start_backup call, tar and
gzip the cluster data directory, issue the pg_stop_backup call, and
remove all previous un-needed WAL files from the archive.

I need to write a regular expression that will search for the WAL
filename and checkpoint location from the backup_label file, and just
want to clarify that the checkpoint location will always be of the
format: X/XXXXXX - where X is one of 0-9, A-F?

And then the WAL .backup file that is generated in the archive, has a
filename of the form:

<WAL_FILE>.00XXXXXX.backup

where <WAL_FILE> is the name of the "STARTING WAL LOCATION" directive in
the backup_label file, and XXXXXX is the last 6 digits of the checkpoint
(after the / )?

Thanks,

Andy.

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Jim C. Nasby

2006-11-09, 5:32 am

On Tue, Nov 07, 2006 at 01:12:53PM +0000, Andy Shellam (Mailing Lists) wrote:
> Hi,
>
> I'm writing an automated file-system level backup application for use
> with WAL archiving, that will issue the pg_start_backup call, tar and
> gzip the cluster data directory, issue the pg_stop_backup call, and
> remove all previous un-needed WAL files from the archive.
>
> I need to write a regular expression that will search for the WAL
> filename and checkpoint location from the backup_label file, and just
> want to clarify that the checkpoint location will always be of the
> format: X/XXXXXX - where X is one of 0-9, A-F?
>
> And then the WAL .backup file that is generated in the archive, has a
> filename of the form:
>
> <WAL_FILE>.00XXXXXX.backup
>
> where <WAL_FILE> is the name of the "STARTING WAL LOCATION" directive in
> the backup_label file, and XXXXXX is the last 6 digits of the checkpoint
> (after the / )?

I don't know the answer, but since no one's replied I suggest looking in
the code. Looking at the source of pg_start_backup would probably be a
good start, though I'm guessing the real answer is somewhere in the
backend.
--
Jim Nasby jim@nasby.net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)

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Andy Shellam

2006-11-09, 5:32 am

Hi Jim,

Tom did answer actually! (Although it was first thing in the morning
and he hadn't had any caffeine so he may have forgot to copy the list in
;) )
I forget what he said the format was now, and I haven't got his e-mail,
but I've just done a regex to match one or more characters before and
after the "/", which works.

Andy.

Jim C. Nasby wrote:
> On Tue, Nov 07, 2006 at 01:12:53PM +0000, Andy Shellam (Mailing Lists) wrote:
>
>
> I don't know the answer, but since no one's replied I suggest looking in
> the code. Looking at the source of pg_start_backup would probably be a
> good start, though I'm guessing the real answer is somewhere in the
> backend.
>

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Simon Riggs

2006-11-14, 7:19 pm

On Tue, 2006-11-07 at 13:12 +0000, Andy Shellam (Mailing Lists) wrote:

> I'm writing an automated file-system level backup application for use
> with WAL archiving, that will issue the pg_start_backup call, tar and
> gzip the cluster data directory, issue the pg_stop_backup call, and
> remove all previous un-needed WAL files from the archive.

Is this any help?

http://archives.postgresql.org/pgsq...05/msg00229.php

If so, I'll see about updating it so it can get backpatched to 8.0 and
8.1 also.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com

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Andy Shellam

2006-11-15, 7:34 pm

Yup that sounds useful - would this be another column added to the
pg_stop_backup called "wal_filename" or similar?
My script uses this name to find the date/time of the current ".backup"
file and remove any files earlier than it (except obviously the one
listed in the START WAL LOCATION).
I've yet to run a restore test, but the backup and automatic archive
clearout is working nicely.

I'm not too worried about the SQL function to find the current WAL file,
although I can see this could be useful too.

Thanks,

Andy.

Simon Riggs wrote:
> On Tue, 2006-11-07 at 13:12 +0000, Andy Shellam (Mailing Lists) wrote:
>
>
>
> Is this any help?
>
> http://archives.postgresql.org/pgsq...05/msg00229.php
>
> If so, I'll see about updating it so it can get backpatched to 8.0 and
> 8.1 also.
>
>

--
Andy Shellam
NetServe Support Team

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