Re: Standby WAL Cleanup?

On Mon, Aug 14, 2017 at 3:58 PM, Guillaume Lelarge <guillaume(at)lelarge(dot)info>
wrote:

>
> The server removes the WAL files it doesn't need anymore, weither it is a
> primary (after a checkpoint) or a secondary node (after a restartpoint).
> That's just part of the usual process.
>

I know the documentation says this about a standalone database regarding
the "archive_command" parameter.

"It is important that the archive command return zero exit status if and
> only if it succeeds. Upon getting a zero result, PostgreSQL will assume
> that the file has been successfully archived, and will remove or recycle
> it."

However on a standby, my understanding is that the archive_command
parameter is not used. I know for sure that it would fail on the standby
that I'm looking at.

Although I did search for restartpoints and see this now:

In archive recovery or standby mode, the server periodically performs
> restartpoints which are similar to checkpoints in normal operation: the
> server forces all its state to disk, updates the pg_control file to
> indicate that the already-processed WAL data need not be scanned again, and *then
> recycles any old log segment files in pg_xlog directory*.

So I guess that's all the info I need then. Is there any to control that
behavior if (for reasons I can't think of right now other than cascading
standby) I wanted to delay that file recycling? Just curious.

Don.
--
Don Seiler
www.seiler.us