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From Ryan King <r...@twitter.com>
Subject Re: cache sizes using percentages
Date Tue, 17 Aug 2010 19:09:12 GMT
On Tue, Aug 17, 2010 at 10:55 AM, Artie Copeland <yeslinux.now@gmail.com> wrote:
> if i set a key cache size of 100% the way i understand how that works is:
> - the cache is not write through, but read through
> - a key gets added to the cache on the first read if not already available
> - the size of the cache will always increase for ever item read.  so if you
> have 100mil items your key cache will grow to 100mil
> Here are my questions:
> if that is the case then what happens if you only have enough mem to store
> 10mil items in your key cache?

Then don't use a percentage.

> do you lose the other 90% how is it determined what is removed?

second-chance fifo.

> will the server keep adding til it gets OOM?

that or a gc storm

> if you add a row cache as well how does that affect your percentage?
> if there a priority between the cache? or are they independant so both will
> try to be satisfied which would result in an OOM?

they are independent

-ryan

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