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From stack <st...@duboce.net>
Subject Re: Scanner Performance Question / Observation
Date Mon, 03 Aug 2009 22:34:00 GMT
On Mon, Aug 3, 2009 at 1:58 PM, Xinan Wu <wuxinan@gmail.com> wrote:

> 6 sec isn't crazy with 0.19. If you really want to research it, have a
> look at where the time is spent, creating scanner or actually doing
> the scanning. I think it's the former.

You are probably right that it is the fomer.  In 0.19, scanners would open a
new Reader against every file in the region before scanning could start
(trip to namenode, then out to each dn to read in indices, etc.).  In
0.20.0, the already-open files are used.

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