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From "LEI Xiaofeng" <le...@ihep.ac.cn>
Subject Re: Re: hbase read performance tuning failed
Date Wed, 08 Jan 2014 01:36:09 GMT
I tried to set "BLOCKSIZE" to 0 when created table to tune the scan performance, but it did
not work. Another thing is what do you mean by "turing HBase checksumming on"? I do not know
how to do it. Could you give mw some detailed information?

Thanks


> -----原始邮件-----
> 发件人: "Doug Meil" <doug.meil@explorysmedical.com>
> 发送时间: 2014年1月8日 星期三
> 收件人: "user@hbase.apache.org" <user@hbase.apache.org>, "lars hofhansl" <larsh@apache.org>
> 抄送: 
> 主题: Re: hbase read performance tuning failed
> 
> 
> 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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