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From Manoj Khangaonkar <khangaon...@gmail.com>
Subject Re: Cassandra slow on some reads
Date Fri, 14 Mar 2014 18:16:13 GMT
>
>
>
> I have ~450 queries that are like this: SELECT * FROM table where key =
> 'some string' and ts = some value; some value is close to present time.
>
> The problem:
>
> About 10 - 20 % of these queries take more than 5 seconds to execute, in
> fact, the majority of those take around 10 seconds.
> When investigating I saw that if I have a slow response and I redo the
> query it will finish in 8 - 10 MILIseconds like the rest of the queries
> that I have.
>
>
>
Most likely for the first slow query, the server has to go looking in
SSTables on disk. 2nd fast response is returned from memory. I am not sure
how much data each node is managing. But try adding more nodes , so that
each node is managing fewer keys. More nodes with recommended heap size of
8G is better than fewer nodes with bigger heap size.

regards

-- 
http://khangaonkar.blogspot.com/

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