Re: detecting binary backup in progress

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On 05/31/2013 10:46 AM, Heikki Linnakangas wrote:
> On 31.05.2013 20:38, Joe Conway wrote:
>> I can check for the presence of $PGDATA/backup_label in order to
>> detect a backup in progress (i.e. pg_start_backup() has been run
>> and pg_stop_backup() has not yet been run).
>>
>> However there is a period of time after pg_start_backup() is
>> first executed to when it completes, during which backup_label
>> file does not exist yet, but the backup has essentially been
>> started. Is there any way to detect this state?
>
> What are you trying to accomplish? Even if you eliminate that
> window, it's always possible that a backup starts just after you've
> checked that there is no backup in progress.

We can lay down a lockfile before checking for backup in progress, and
the script that starts the backup can check for the lockfile before
doing anything. There is still a race-window, but I want to minimize
it. pg_is_in_backup() mentioned nearby on this thread will help close
the gap.

Joe

- --
Joe Conway
credativ LLC: http://www.credativ.us
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