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HBase, mail # user - Short-circuit reads


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Re: Short-circuit reads
Ted Yu 2013-01-27, 22:45
J-D's presentation can give you some idea about the speedup:
http://files.meetup.com/1350427/hug_ebay_jdcryans.pdf

Thanks

On Sun, Jan 27, 2013 at 2:38 PM, Jean-Marc Spaggiari <
[EMAIL PROTECTED]> wrote:

> Does this have a significant increase on HBase performances? And what
> are the "risks" associated with short-circuit activation (if any)? No
> risks of corrupting data?
>
> Can this be activated after tables are already populated?
>
> JM
>
> 2013/1/27, Ted <[EMAIL PROTECTED]>:
> > For hbase internal checksum, it is not in hbase 0.92.x release.
> >
> > Please use 0.94.2 or newer release.
> >
> > Thanks
> >
> > On Jan 27, 2013, at 2:29 PM, David Koch <[EMAIL PROTECTED]> wrote:
> >
> >> Hello,
> >>
> >> I read about "short circuit reads" in the HBase documentation's
> >> performance
> >> section[1] and was wondering what people's experiences were using this
> in
> >> a
> >> production setting.
> >>
> >> Also,
> >>
> >> 1. Since only one dedicated user can take advantage of the feature do
> you
> >> launch all jobs as this user?
> >> 2. Can dfs.client.read.shortcircuit be set to false for jobs wich are
> not
> >> launched by the short-circuit user in order to avoid exceptions? In
> other
> >> words - can this setting be overriden by the client configuration's
> >> hbase-site.xml?
> >> 3. In the same context, it is suggested to enable HBase internal
> >> checksums[2]. Is this a feature which can be enabled in HBase 0.92.1
> >> which
> >> is part of the Cloudera 4.1.x release?
> >>
> >> Thank you,
> >>
> >> /David
> >>
> >> [1] http://hbase.apache.org/book/perf.hdfs.html#ftn.d2145e7370
> >> [2] https://issues.apache.org/jira/browse/HBASE-5074
> >
>