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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Read Performance
Date Wed, 31 Mar 2010 18:44:26 GMT
But then you'd still be caching the same things memcached is, so
unless you have a lot more ram you'll presumably miss the same rows
too.

The only 2-layer approach that makes sense to me would be to have
cassandra keys cache at 100% behind memcached for the actual rows,
which will actually reduce the penalty for a memcache miss by
half-ish.

On Wed, Mar 31, 2010 at 1:32 PM, David Strauss <david@fourkitchens.com> wrote:
> Or, if faking memcached misses is too high a price to pay, queue some
> proportion of the reads to replay asynchronously against Cassandra.
>
> On Wed, 2010-03-31 at 11:04 -0500, Jonathan Ellis wrote:
>> Can you redirect some of the reads from memcache to cassandra?  Sounds
>> like the cache isn't getting warmed up.
>>
>> On Wed, Mar 31, 2010 at 11:01 AM, James Golick <jamesgolick@gmail.com> wrote:
>> > I'm testing on the live cluster, but most of the production reads are being
>> > served by the cache. It's definitely the right CF.
>> >
>> > On Wed, Mar 31, 2010 at 8:30 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
>> >>
>> >> On Wed, Mar 31, 2010 at 12:01 AM, James Golick <jamesgolick@gmail.com>
>> >> wrote:
>> >> > Okay, so now my row cache hit rate jumps between 1.0, 99.5, 95.6, and
>> >> > NaN.
>> >> > Seems like that stat is a little broken.
>> >>
>> >> Sounds like you aren't getting enough requests for the
>> >> getRecentHitRate to make sense.  use getHits / getRequests.
>> >>
>> >> But if you aren't getting enough requests for getRecentHitRate, are
>> >> you sure you're tuning the cache on the right CF for your 35ms test?
>> >> Are you testing live?  If not, what's your methodology here?
>> >>
>> >> -Jonathan
>> >
>> >
>
>
>
>

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