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From "Jean-Daniel Cryans" <jdcry...@gmail.com>
Subject Re: HQL usage
Date Tue, 22 Jul 2008 14:06:10 GMT
 1) why is having a query language mutual exclusive to HBase goals?

Using SQL-like languages for HBase proved. to this date, to be more
confusing than helpful. Seeing questions like "why is there no joins?" or
"where can I find a JDBC connector to HBase?" overkilled the fact the, to
this point, HQL was used only for administration purposes (maybe the
original goal of HQL was different but this will not be discussed in this
answer). So is it mutually exclusive to HBase? No, I don't think so, but if
such language is ever officially developed it will be a very crippled one
like GQL.

HBase is basically a map with enhanced features, so why not using it
according to it's nature? MapReduce is also a good way to manipulate your
data in batch btw.

2) what is the expected integration point to a J2EE application for HBase?

I personally use HBase in a small project based on Spring (which is not JEE,
I agree, but near) and it proved to be easy to integrate behind some DAO.
But something is important to note: Bigtable is born because typical RDBMS
cannot provide enough scalability, availability and performance on a very
huge scale. If your are reaching a point where all your shards of
master-slave replicated MySQL cannot handle your load, you already gave up
normalization a long long time ago. At that scale, all you want to have is a
single place to store your data and you don't mind handling the rest. There
is no recipe, no framework that will help you unless you paid millions to
have ultra-specialized hardware and software (which is note HBase goal).

So, really, there is for the moment no answer to your question apart from
"try something, if it works, publish it!".

Hope that helped understanding HBase. On a separate note, an HBase
implementation of GAE is on the "nice to have" list. If you would like to
contribute, we would all be glad.



On Tue, Jul 22, 2008 at 3:39 AM, lucio Piccoli <lucio_piccoli@hotmail.com>

> > Disabuse yourself of any notion that hbase is an RDBMS.  There's no SQL,
> > JDBC, hibernate connector, etc.
> perhaps not SQL/JDBC but a query language like HQL.
> since there are many comparisons betwen HBase and google bigtable, i was
> hoping for a query capability found in GAE.
> http://code.google.com/appengine/docs/datastore/queriesandindexes.html
> # The GqlQuery interface prepares a query using a GQL query string.
> q = db.GqlQuery("SELECT * FROM Person " +
>                "WHERE last_name = :1 AND height < :2 " +
>                "ORDER BY height DESC",
>                "Smith", 72)
> as u can see the query language is very similar to SQL and easy to use.
> > Going by your questions above, I'd suggest you do a little background
> > reading so you get better sense of what hbase is about.  Start in with
> > the hbase architecture paper up on our wiki:
> > http://wiki.apache.org/hadoop/Hbase.   Feel free to ask questions in
> > here in this forum if there is anything you need help with.
> i have read the docs and was hoping for GAE like functionality to access
> the datastore.
> so my questions are
> 1) why is having a query language mutual exclusive to HBase goals?
> 2) what is the expected integration point to a J2EE appllication for HBase?
> any help is appreciated.
> -lucio
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