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From aaron morton <aa...@thelastpickle.com>
Subject Re: Single column read latency
Date Fri, 09 Mar 2012 18:08:11 GMT
Check the latency on the server, use nodetool cfstats. Call it before the request to recent
the "recent" latency.

Then dive into nodetool cfhistogram to see how much effort went into retrieving the request.

Cheers

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 9/03/2012, at 9:38 AM, A J wrote:

> Hello,
> In a CF I have with valueless columns and column-name type being
> integer, I am seeing latency in the order of 80-90ms to retrieve a
> single column from a row containing 50K columns. It is just a single
> node db on a single box.
> Another row with 20K columns in the same CF, still has the latency
> around 30ms to get to a single column.
> 
> Example in pycassa, for a row with 50K columns:
> t1 = time.time()
> cf1.get(5011,columns=[90006111])
> t2 = time.time() - t1
> print  int(t2*1000),'ms'
> 
> gives 82 ms
> 
> Any idea what could be causing the latency to be so high ? That too
> after ensuring that the row_cache is large enough to contain all the
> rows and all the rows are pre-fetched.
> 
> Thanks.


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