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From "Bin YANG" <yangbinism...@gmail.com>
Subject Re: Does HBase have a index?
Date Thu, 06 Mar 2008 10:18:29 GMT
Dear Edward Yoon,

What I want to know is how HBase to execute the HQL query.

I know that the SELECT in HQL can just specify row keys in WHERE clause.
If I want to make the WHERE support column=***, I think HBase need indices.
So, I want to know how does "WHERE row keys = ***" do now.

About the column-oriented database, I know C-Store is a example.
C-Sotre is a complete relational database, while the bigtable is not a
relational database.
Bigtable just supports to store simple relational data. So that, I
think Bigtable should have
different index models compared with column-oriented database.

I think CAN is one of the Distributed Hash Table, maybe CHORD, PASTRY
is similar to CAN.
DHT can store data as a key find the data according to the key, but it
cannot support store data with locality.
For example, if you want to store two webpage form same site in one
node, the bigtable can assure the requirement,
but the DHT cannot assure. Using DHT, the two webpage may store in two
nodes, because the content of the two
pages are different.

What is your opinion on how to support powerful HQL in HBase or Bigtable?

Cheers,
Bin YANG

On Thu, Mar 6, 2008 at 5:55 PM, edward yoon <edward@udanax.org> wrote:
> >> I suppose that a hash function which hash row key to physical address
>  is more efficient.
>
>  Actually, I thought and consider about CAN (Content-Addressable
>  Network) because BigTable has a immutable meta tree as a b+tree.
>  I don't exactly know what do you think, but it is a revolutionary idea.
>
>  If I may digress from my theme for a moment,
>  For 30 years, The benefits of column-store development has been the
>  subject of much/some debate. but, the availability of column-store has
>  not been authenticated.
>  And also, i couldn't proof an benefits of Hbase (BigTable clone)
>  because there is an various alternative suggestions. But, I recently
>  find a answer that they only made a BigTable for fun.
>
>
>
>  On 3/6/08, Bin YANG <yangbinisme82@gmail.com> wrote:
>  > Dear colleagues,
>  >
>  >  I have a questions on HBase's index implementation.
>  >
>  >  How does the HBase find the data according to a row key? Use a index
>  >  like database, or use a hash function?
>  >  I suppose that a hash function which hash row key to physical address
>  >  is more efficient.
>  >
>  >  As we know, a big table in HBase is stored as several Small tables,
>  >  each table stores attributes in a column family.
>  >  So that, each row may be stored in several small tables.
>  >  Does a hash function hash row key to many physical address? Each
>  >  physical address correspond to a small table which contains the row
>  >  key?
>  >
>  >  Does anybody have idea on how to create a index on other attribute?
>  >
>  >  Best,
>  >  Bin YANG
>  >
>  > --
>  >  Bin YANG
>  >  Department of Computer Science and Engineering
>  >  Fudan University
>  >  Shanghai, P. R. China
>  >  EMail: yangbinisme82@gmail.com
>  >
>
>
>  --
>  B. Regards,
>  Edward yoon @ NHN, corp.
>



-- 
Bin YANG
Department of Computer Science and Engineering
Fudan University
Shanghai, P. R. China
EMail: yangbinisme82@gmail.com

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