Re: Problem with PITR recovery

Alvaro Herrera wrote:
> On Tue, Apr 19, 2005 at 11:05:32AM -0400, Bruce Momjian wrote:
> > Simon Riggs wrote:
>
> > > The disk would only fill if the archiver doesn't keep up with
> > > transmitting xlog files to the archive. The archive can fill up if it is
> > > not correctly sized, even now. Switching log files every N seconds would
> > > at least give a very predictable archive sizing calculation which should
> > > actually work against users sizing their archives poorly.
> >
> > I was thinking of the archiver filling because of lots of almost-empty
> > 16mb files. If you archive every five seconds, it is 11 Gigs/hour,
> > which is not too bad, I guess, but I would bet compression would save
> > space and I/O load too.
>
> I suggested back then that some command to replace an archive could be
> provided. So some people could use rsync to update the older version of
> the XLog file to the new state. Non-rsync enabled people could use a
> temporary file to copy the new file, and then rename to the original
> XLog name, substituting the older version. And as a third way, maybe we
> can come up with a sort-of-xdelta that would only update the yet-unused
> portion of the old xlog file to the new content. (Maybe this could be
> made to work with tape.)
>
> Everyone here said that there was no need for such a thing because it
> would complicate matters.

I do think we are going to need to go in that direction. I think the
problem is that we didn't have enough time to come up with a clear
solution to this problem so we delayed it for 8.1.

I agree the idea of overwriting is a nice idea and works for everything
but a tape drive, so it has to be optional in some way.

--
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