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From Eran Chinthaka Withana <eran.chinth...@gmail.com>
Subject Re: Key cache hit rate issue
Date Wed, 15 Feb 2012 00:00:31 GMT
Its in the order of 261 to 8000 and the ratio is 0.00. But i guess 8000 is
bit high. Is there a way to fix/improve it?

Thanks,
Eran Chinthaka Withana


On Tue, Feb 14, 2012 at 3:42 PM, aaron morton <aaron@thelastpickle.com>wrote:

> Out of interest what does cfstats say about the bloom filter stats ? A
> high false positive could lead to a low key cache hit rate.
>
> Also, is there a way to warm start the key cache, meaning pre-load the
> amount of keys I set as keys_cached?
>
> See key_cache_save_period when creating the CF.
>
> Cheers
>
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 15/02/2012, at 5:54 AM, Eran Chinthaka Withana wrote:
>
> Hi,
>
> I'm using Cassandra 1.0.7 and I've set the keys_cached to about 80% (using
> the numerical values). This is visible in cfstats too. But I'm getting less
> than 20% (or sometimes even 0%) key cache hit rate. Well, the data access
> pattern is not the issue here as I know they are retrieving the same row
> multiple times. I'm using hector client with dynamic load balancing policy
> with consistency ONE for both reads and writes. Any ideas on how to find
> the issue and fix this?
>
> Here is what I see on cfstats.
>
> Key cache capacity: 16637958
> Key cache size: 16637958
> Key cache hit rate: 0.045454545454545456
>
> Also, is there a way to warm start the key cache, meaning pre-load the
> amount of keys I set as keys_cached?
>
> Thanks,
> Eran
>
>
>

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