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From Boris Aleksandrovsky <balek...@gmail.com>
Subject Re: HBase is very slow on full table scan
Date Mon, 08 Feb 2010 22:57:14 GMT
I am using HTable.setScannerCaching(10) and the size of the row is variable
from 10 to 100K (approx). Should I increase the scan cache size?

On Mon, Feb 8, 2010 at 2:47 PM, Jean-Daniel Cryans <jdcryans@apache.org>wrote:

> How big are the rows and are you using:
>
>
> http://hadoop.apache.org/hbase/docs/r0.20.3/api/org/apache/hadoop/hbase/client/Scan.html#setCaching(int)<http://hadoop.apache.org/hbase/docs/r0.20.3/api/org/apache/hadoop/hbase/client/Scan.html#setCaching%28int%29>
>
> thx
>
> J-D
>
> On Mon, Feb 8, 2010 at 2:43 PM, Boris Aleksandrovsky <baleksan@gmail.com
> >wrote:
>
> > Hi,
> >
> > I have noticed that the performance of the full table scan (table
> contains
> > about 5M rows) is extremely slow in our case. We are running 0.20.2,
> > r834515
> > and it takes about 3 min / 5000 rows to scan the table.
> >
> > We have 3 region servers on 3 different machines with the following
> > characteristics:
> >
> > server11265576122987requests=0, regions=124, usedHeap=1468, maxHeap=2983
> > server21265576119422requests=4, regions=121, usedHeap=1482, maxHeap=2983
> > server31265576119423requests=44, regions=117, usedHeap=1570, maxHeap=2983
> > The "slow" table in question is configured as following:
> >
> > Table = {NAME => 'post', FAMILIES => [{NAME => 'ngrams', VERSIONS =>
'3',
> > COMPRESSION => 'NONE', TTL => '2147483647', BLOCKSIZE => '65536',
> IN_MEMORY
> > => 'false', BLOCKCACHE => 'true'}]}
> >
> > There is nothing suspicious in the log, as far as I can tell.
> >
> > Please let me know if you need more information about our installation
> >
> > --
> > Thanks,
> >
> > Boris
> >
>



-- 
Thanks,

Boris
http://twitter.com/baleksan
http://www.linkedin.com/in/baleksan

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