Re: Proposing pg_hibernate

On Thu, May 29, 2014 at 12:12 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> IMHO, all of these caveats, would affect a very small fraction of
>> use-cases and are eclipsed by the benefits this extension provides in
>> normal cases.
>
> I agree with you that there are only few corner cases where evicting
> shared buffers by this utility would harm, but was wondering if we could
> even save those, say if it would only use available free buffers. I think
> currently there is no such interface and inventing a new interface for this
> case doesn't seem to reasonable unless we see any other use case of
> such a interface.

It seems like it would be best to try to do this at cluster startup
time, rather than once recovery has reached consistency. Of course,
that might mean doing it with a single process, which could have its
own share of problems. But I'm somewhat inclined to think that if
recovery has already run for a significant period of time, the blocks
that recovery has brought into shared_buffers are more likely to be
useful than whatever pg_hibernate would load.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company