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From Jeffrey Kesselman <jef...@gmail.com>
Subject Re: How to reduce the Read Latency.
Date Fri, 20 May 2011 08:25:47 GMT
What consistency are you asking for?

On Fri, May 20, 2011 at 7:42 AM, Dikang Gu <dikang85@gmail.com> wrote:
> Hi All,
> I'm running three cassandra 0.7.4 nodes in a cluster, and I give 2G memory
> to each node.
> Now, I get the cfstats here:
> Keyspace: UserMap
> Read Count: 38411
> Read Latency: 123.54214613001484 ms.
> Write Count: 44155
> Write Latency: 0.02341093873853471 ms.
> Pending Tasks: 0
> Column Family: Map
> SSTable count: 3
> Space used (live): 32704387
> Space used (total): 32704387
> Memtable Columns Count: 49
> Memtable Data Size: 3348
> Memtable Switch Count: 56
> Read Count: 38411
> Read Latency: 123.542 ms.
> Write Count: 44155
> Write Latency: 0.023 ms.
> Pending Tasks: 0
> Key cache capacity: 200000
> Key cache size: 611
> Key cache hit rate: 0.9294361241314483
> Row cache: disabled
> Compacted row minimum size: 125
> Compacted row maximum size: 17436917
> Compacted row mean size: 147647
> You can find that the Read Latency is really high here, so what can I do to
> reduce the latency?  Give more memory to the three nodes? Any other options?
> Thanks.
> --
> Dikang Gu
> 0086 - 18611140205
>



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