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From Ted Yu <yuzhih...@gmail.com>
Subject Re: short scans in one RPC
Date Fri, 23 Aug 2013 01:02:53 GMT
Interesting idea.


On Thu, Aug 22, 2013 at 9:53 AM, Dave Latham <latham@davelink.net> wrote:

> I was recently dealing with a situation of the META table being slammed
> with queries for a long time.  While evaluating the problem I saw the IPCs
> being in a cycle like the following:
>
> HRegionInterface#getClosestRowBefore queueTime=200 processingTime=1 ... 444
> bytes.
> HRegionInterface#openScanner queueTime=191 processingTime=0 ... 22 bytes.
> HRegionInterface#next queueTime=154 processingTime=1 ...  4551 bytes.
> HRegionInterface#close queueTime=216 processingTime=0 ... 16 bytes.
> (rinse, repeat)
>
> I'm bumping our prefetching from 10 rows to 50 rows to help cut down on the
> number of cycles, but it also occurs to me that it's a bit painful to
> require 3 RPCs to do a short scan.
>
> What would people think about adding method for short scans which
> encapsulates (openScanner / next / close) in a single RPC?
>
> Dave
>

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