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From Michael Segel <michael_se...@hotmail.com>
Subject Re: Many scanner opening
Date Thu, 20 Dec 2012 13:14:00 GMT
I'd suggest looking in to a schema design change.

On Dec 18, 2012, at 2:01 AM, Eugeny Morozov <emorozov@griddynamics.com> wrote:

> Hello!
> 
> We faced an issue recently that the more map tasks are completed, the
> longer it takes to complete one more map task.
> 
> In our architecture we have two scanners to read the table. The first one,
> which is called 'outer' scanner is reading table and filter some rowkeys.
> These rowkeys are used as a filter for second scanner - 'internal'. Thus we
> constantly open 'internal' scanner with different filters.
> 
> As an additional symptoms we see that our cluster practically does nothing
> - there is no CPU loading, no disk loading, no network, etc. Most of the
> time it means we are waiting on some locks, but I'm not sure.
> 
> I would appreciate any ideas or suggestions to understand the case.
> Thank you in advance.
> -- 
> Evgeny Morozov
> Developer Grid Dynamics
> Skype: morozov.evgeny
> www.griddynamics.com
> emorozov@griddynamics.com


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