Re: Automatic cleanup of oldest WAL segments with pg_receivexlog

On Mon, Mar 6, 2017 at 3:26 PM, Peter Eisentraut
<peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> On 3/4/17 02:09, Michael Paquier wrote:
>> Well, that's one reason why I was thinking that having an independent
>> in-core option to clean up the tail of the oldest segments is
>> interesting: users don't need to maintain their own infra logic to do
>> anything. Now this end-segment command can as well be used with a
>> small binary doing this cleanup, but the monitoring of the thing gets
>> harder as multiple processes get spawned.
>
> I think the initial idea of having an option that does something
> specific is better than an invitation to run a general shell command. I
> have some doubts that the proposal to clean up old segments based on
> file system space is workable. For example, that assumes that you are
> the only one operating on the file system. If something else fills up
> the file system, this system could then be induced to clean up
> everything immediately, without any reference to what you still need.
> Also, the various man pages about statvfs() that I found are pretty
> pessimistic about how portable it is.

What if we told pg_receivewal (or pg_receivexlog, whatever that is) a
maximum number of segments to retain before removing old ones? Like
pg_receivewal --limit-retained-segments=50GB, or something like that.

--
Robert Haas
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