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From Dikang Gu <dikan...@gmail.com>
Subject How to reduce the Read Latency.
Date Fri, 20 May 2011 07:42:42 GMT
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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