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From Lin Ma <lin...@gmail.com>
Subject Re: Using HBase serving to replace memcached
Date Wed, 22 Aug 2012 12:11:32 GMT
Thanks Zahoor,

I read through the document you referred to, I am confused about what means
leaf-level index, intermediate-level index and root-level index. It is
appreciate if you could give more details what they are, or point me to the
related documents.

BTW: the document you pointed me is very good, however I miss some basic
background of 3 terms I mentioned above. :-)

regards,
Lin

On Wed, Aug 22, 2012 at 12:51 PM, J Mohamed Zahoor <jmozah@gmail.com> wrote:

> I could be wrong. I think HFile index block (which is located at the end
>> of HFile) is a binary search tree containing all row-key values (of the
>> HFile) in the binary search tree. Searching a specific row-key in the
>> binary search tree could easily find whether a row-key exists (some node in
>> the tree has the same row-key value) or not. Why we need load every block
>> to find if the row exists?
>>
>>
> Hmm...
> It is a multilevel index. Only the root Index's (Data, Meta etc) are
> loaded when a region is opened. The rest of the tree (intermediate and leaf
> index's) are present in each block level.
> I am assuming a HFile v2 here for the discussion.
> Read this for more clarity http://hbase.apache.org/book/apes03.html
>
> Nice discussion. You made me read lot of things. :-)
> Now i will dig in to the code and check this out.
>
> ./Zahoor
>

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