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From Doug Meil <doug.m...@explorysmedical.com>
Subject Re: hbase read performance tuning failed
Date Tue, 07 Jan 2014 20:43:27 GMT

In addition to what Lars just said about the blocksize, this is a similar
question to another one that somebody asked, and it's always good to make
sure that you understand where your data is. As a sanity check, make sure
it's not all on one or two RSs (look at the hbase web pages or with tools
like Hannibal).


Also, you definitely want to to turn HBase checksumming on - and when you
do so you'll need to re-create the HFiles (e.g., you can't just change the
config and bounce the HBase cluster).  That's a significant reduction in
I/O.

Likewise, if you are doing a full-scan, make sure that you select only the
attributes you need...

See this for more:  http://hbase.apache.org/book.html#perf.reading





On 1/7/14 1:24 PM, "lars hofhansl" <larsh@apache.org> wrote:

>If increasing hbase.client.scanner.caching makes no difference you have
>another issue.
>How many rows do you expect your to return?
>
>On contemporary hardware I manage to scan a few million KeyValues (i.e.
>columns) per second and per CPU core.
>Note that for scan performance you want to increase the BLOCKSIZE.
>
>
>-- Lars
>
>
>
>________________________________
> From: LEI Xiaofeng <leixf@ihep.ac.cn>
>To: user@hbase.apache.org
>Sent: Monday, January 6, 2014 11:06 PM
>Subject: hbase read performance tuning failed
> 
>
>Hi,
>I am running hbase-0.94.6-cdh4.5.0 and set up a cluster of 5 nodes. The
>random read performance is ok, but the scan performance is poor.
>I tried to increase "hbase.client.scanner.caching" to 100 to promote the
>scan performance but it made  no difference. And when I tried to make
>smaller blocks by setting "BLOCKSIZE" when created tables to get better
>random read performance it made no difference too.
>So, I am wondering if anyone could give some advice to solve this problem.
>
>
>
>Thanks


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