Re: Maximum number of WAL files in the pg_xlog directory

Sorry for my very late answer. It's been a tough month.

2014-11-27 0:00 GMT+01:00 Bruce Momjian <bruce(at)momjian(dot)us>:

> On Mon, Nov 3, 2014 at 12:39:26PM -0800, Jeff Janes wrote:
> > It looked to me that the formula, when descending from a previously
> stressed
> > state, would be:
> >
> > greatest(1 + checkpoint_completion_target) * checkpoint_segments,
> > wal_keep_segments) + 1 +
> > 2 * checkpoint_segments + 1
>
> I don't think we can assume checkpoint_completion_target is at all
> reliable enough to base a maximum calculation on, assuming anything
> above the maximum is cause of concern and something to inform the admins
> about.
>
> Assuming checkpoint_completion_target is 1 for maximum purposes, how
> about:
>
> max(2 * checkpoint_segments, wal_keep_segments) + 2 *
> checkpoint_segments + 2
>
>
Seems something I could agree on. At least, it makes sense, and it works
for my customers. Although I'm wondering why "+ 2", and not "+ 1". It seems
Jeff and you agree on this, so I may have misunderstood something.

--
Guillaume.
http://blog.guillaume.lelarge.info
http://www.dalibo.com