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From James Golick <jamesgol...@gmail.com>
Subject Re: Read Performance
Date Wed, 31 Mar 2010 04:11:12 GMT
No change observed. The hit rate fluctuates between 0.0, 0.3, and NaN every
time I run cfstats.

I just increased it by 10x. Hopefully that'll help.

On Tue, Mar 30, 2010 at 8:59 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> What is your row cache hit rate?
>
> By "still slow" do you mean "no change observed" or "faster but not
> fast enough?"
>
> On Tue, Mar 30, 2010 at 10:47 PM, James Golick <jamesgolick@gmail.com>
> wrote:
> > We are starting to use cassandra to power our activity feed. The way we
> > organize our data is simple. "Event"s live in a CF called Events and are
> > keyed by a UUID. The timelines themselves live in a CF called Timelines,
> > which is keyed by user id (i.e. "1229") and contains a event uuids as
> column
> > names (sorted by TimeUUIDType).
> > To load a feed, we get a slice of the timeline CF for that user, then
> > multiget all of the corresponding events.
> > Loading the slice of the timeline is reasonably fast at 4-6ms. But,
> > multigetting the events is terribly slow - on the order of 35-100ms.
> > To alleviate the problem, we write events through to memcached and use a
> > memcached multiget in front of the cassandra multiget. We have enough
> cache
> > space to get upwards of a 99% hit rate, which makes loading the events
> > extremely fast, but it would be nice to make use of the 24GB of memory in
> > our cassandra nodes.
> > We're on 0.6, and I've enabled the row cache. It seems to have data in
> it,
> > but it's still slow.
> > So, am I doing something wrong, or is this the expected perf?
> > - James
>

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