Re: Syscaches should store negative entries, too

On Wed, 2002-01-30 at 10:56, Tom Lane wrote:
>
> FWIW, I believe that in typical scenarios there *is* no competition as
> the syscache never gets full enough to have anything age out.  In the
> regression tests my little stats addition shows no run with more than
> 266 cache entries accumulated; the average end-of-run cache population
> is 75 entries.  Syscache is currently configured to allow 5000 entries
> before it starts to drop stuff.

Are there _any_ tests where it does start to drop stuff ?

In other words - is the stuff-dropping part tested reasonably recently
(or at all) ?

> The regression tests are probably not representative, but if anything
> I'd expect them to hit a wider variety of tables on an average run than
> typical applications do.
> 
> Bottom line: it's not apparent to me why the cache policy should be
> anything but straight LRU across both positive and negative entries.

In other words we should cache Frequently Asked Questions and not
Frequently Found Answers ;)

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Hannu