Re: pg_start_backup does not actually allow for consistent, file-level backup

On 06/08/2015 06:26 AM, otheus uibk wrote:
> On Mon, Jun 8, 2015 at 3:13 PM, otheus uibk <otheus(dot)uibk(at)gmail(dot)com
> <mailto:otheus(dot)uibk(at)gmail(dot)com>> wrote:
>
> Thank you, all. The manual for 9.4 is indeed clearer on this point
> than the 9.1 version.
>
>
> Just to nit-pick, I see nowhere in either version of the manual the
> indication that it is normal for postgresql to continue to update files
> in its data catalog between pg_start_backup and pg_stop_backup. The
> closest I see comes in this paragraph:
>
> ** Some file system backup tools emit warnings or errors if the files
> they are trying to copy change while the copy proceeds. When taking a
> base backup of an active database, this situation is normal and not an
> error.
>
> Does "this situation" refer to the tools emitting warnings or to the
> fact that postgresql is updating the files? It might be the case, for
> instance, that timestamps are updated but not the contents of the files
> (this is what I had assumed prior to today).

Not sure what you are using these backups for, but have you looked at?:

http://www.postgresql.org/docs/9.4/static/app-pgbasebackup.html

>
> --
> Otheus
> otheus(dot)uibk(at)gmail(dot)com <mailto:otheus(dot)uibk(at)gmail(dot)com>
> otheus(dot)shelling(at)uibk(dot)ac(dot)at <mailto:otheus(dot)shelling(at)uibk(dot)ac(dot)at>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com