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Date: Thu, 13 Jan 2011 11:01:08 -0800
Message-ID: <AANLkTi=Ho3HR3MUvazQvdcWCmnTzC2jeXHhkaqQ6JSR-@mail.gmail.com>
Subject: Re: cassandra row cache
From: Jonathan Ellis <jbellis@gmail.com>
To: user <user@cassandra.apache.org>
Content-Type: text/plain; charset=ISO-8859-1

does the cache size change between 2nd and 3rd time?

On Thu, Jan 13, 2011 at 10:47 AM, Saket Joshi <sjoshi@touchcommerce.com> wrote:
> Hi,
>
> I am running a 15 node cluster ,version 0.6.8, Linux 64bit OS, using mmap
> I/O, 6GB ram allocated. I have row cache enabled to 80000 keys (mean row
> size is 2KB). I am observing a strange behaviour.. I query for 1.6 Million
> rows across the cluster and time taken is around 40 mins , I query the same
> data again , the time now is 25 mins to fetch data (i am expecting the cache
> to be warm now) , but i see row cache hit rate around 30% . Now i request
> the same data 3rd time, time to fetch is under 4 mins and cache hit ratios
> are 99% ... Does any one have an idea why this may be happening ?
>
>
>
>
>
> Thanks,
>
> Saket


-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com