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From Weiwei Xiong <xion...@gmail.com>
Subject Re: IN_MEMORY setting
Date Sat, 09 Jul 2011 20:28:55 GMT
Thank you guys so much for your explanations. I am now more clear with the
IN_MEMORY setting.
I will also try to use the APIs mentioned by Doug.

Thanks,
ww

On Fri, Jul 8, 2011 at 7:14 PM, Doug Meil <doug.meil@explorysmedical.com>wrote:

>
> Weiwei, in addition to what Andy said you have control over what is used
> in the block cache in your queries.  See <Get>.setCacheBlocks and
> <Scan>.setCacheBlocks.  These are true by default.
>
>
>
> Thanks Andy for the explanation, the Hbase book doesn┬╣t explain this
> enough.  I'll submit a patch.
>
>
>
>
>
>
> On 7/8/11 9:40 PM, "Andrew Purtell" <apurtell@apache.org> wrote:
>
> >IN_MEMORY means that HBase will try really hard to keep all of the data
> >blocks for a table in the block cache. Block cache is expired on a LRU
> >basis in three priority bands. Blocks for IN_MEMORY tables have the
> >highest priority. They will be the last to be evicted.
> >
> >It does not mean data is never written to disk -- all data in HBase is
> >backed by files in HDFS.
> >
> >It does not mean the table data won't be evicted if the table becomes
> >very large and it cannot all fit in the available configured block cache.
> >
> >Best regards,
> >
> >
> >   - Andy
> >
> >Problems worthy of attack prove their worth by hitting back. - Piet Hein
> >(via Tom White)
> >
> >
> >----- Original Message -----
> >> From: Weiwei Xiong <xiongww@gmail.com>
> >> To: user@hbase.apache.org
> >> Cc:
> >> Sent: Friday, July 8, 2011 6:04 PM
> >> Subject: IN_MEMORY setting
> >>
> >> Hi all,
> >>
> >> Is there anyway to always keep a table in memory? Will IN_MEMORY setting
> >> server this purpose?
> >>
> >> Thanks,
> >> ww
> >>
>
>

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