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From "Jean-Daniel Cryans" <jdcry...@apache.org>
Subject Re: Querying
Date Thu, 11 Sep 2008 22:37:56 GMT

Answers inline.


On Thu, Sep 11, 2008 at 12:39 AM, Ryan LeCompte <lecompte@gmail.com> wrote:

> Hello all,
> I have a question regarding querying data that is in HBase. Is there a
> way to fairly efficiently query, e.g. all rows where the row key is a
> certain value?

All rows where the row key is a certain value? They are unique and it`s a
matter of doing a "get".

> Does HBase API provide some sort of query interface
> besides a Scanner to just get all the rows that have a certain column
> family:column_qualifier?

The is no "secondary" index for the moment in HBase. To do this, you have to
build aggregate tables.

> What would you say are the limits of the
> existing HBase query API?

Your imagination?

> Can a Hadoop map/reduce job take hbase data
> as input and process/query it in an efficient manner?

See http://wiki.apache.org/hadoop/Hbase/MapReduce
It is efficient in the way that it is easy to do it. Fast? Well it can be
better, also true for the rest of HBase (since performance is not our
current focus).

> Sorry if these
> questions don't make sense -- just started learning HBase this
> evening.

I would also recommend reading the Bigable paper.

> Thanks!
> Ryan

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