Re: Figuring out shared buffer pressure

On Thu, May 31, 2012 at 10:11 AM, Bruce Momjian <bruce@momjian.us> wrote:
> However, this doesn't help people configure shared buffers larger (e.g.
> 35%) if their working set is larger.  Right now, I don't see how a user
> would know this is happening.  On the flip side, they might have a
> smaller working set than 25% and spending the overhead of managing 1
> million shared buffers.  Again, there is no way to know if that is the
> case.

Another important use case: downgrades.  They do happen, and right now
are amazingly risky and made with limited information.  Clearly a most
complete picture is impossible because of reliance on kernel buffer
management, but knowing the PG buffer pool occupancy and flux seems
like it'd be so much better than knowing nothing, and it is likely
that some conservative intuition could be learned to perform
relatively safe downgrades.

--
fdr