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From Sever Fundatureanu <fundatureanu.se...@gmail.com>
Subject Re: In memory table after using 'alter'
Date Thu, 28 Jun 2012 13:54:10 GMT
Thanks, Minh.
This blog also mentions that bloom filters check "if a given column exists
in a given row". However in "HBase: The definitive guide" it is mentioned
that "enabling the Bloom filter does give you the immediate advantage of
knowing if a file contains a particular row key or not". Is the blog post a
bit outdated?

Thanks,
Sever


On Wed, Jun 27, 2012 at 6:00 PM, Minh Duc Nguyen <mdnguyen@gmail.com> wrote:

> Sever, the IN_MEMORY option doesn't change when table content is
> transferred into RAM.  Whether set to true or false, the blocks of
> data are only loaded into memory after a normal retrieval operation.
> When IN_MEMORY is set to true, HBase just tries to keep data in memory
> more aggressively than it normally would.  This wiki explains it in
> more detail:
>
>
> http://jimbojw.com/wiki/index.php?title=Understanding_HBase_column-family_performance_options
>
>   ~ Minh
>
> On Wed, Jun 27, 2012 at 7:18 AM, Sever Fundatureanu
> <fundatureanu.sever@gmail.com> wrote:
> > Hello,
> >
> > I initially created a table without the IN_MEMORY option enabled and
> loaded
> > some data into it. Then I disabled it, modified the IN_MEMORY option
> using
> > the hbase shell 'alter' command, re-enabled it and finally ran a major
> > compaction. I do notice now the memory usage of the region servers has
> > increased. However for some queries I am still getting faster responses
> > only the 2nd time, as if I'm hitting the cache. Can someone tell me when
> > does the table content get transferred into RAM if IN_MEMORY option is
> > enabled like above?
> >
> > Thank you,
> > --
> > Sever Fundatureanu
> >
> > Vrije Universiteit Amsterdam
> > E-mail: fundatureanu.sever@gmail.com
>



-- 
Sever Fundatureanu

Vrije Universiteit Amsterdam
Tel: +31644329534
E-mail: fundatureanu.sever@gmail.com

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