Re: federate several datasources

From: Robert Klemme (bob.news_at_gmx.net)
Date: 12/13/04 

Date: Mon, 13 Dec 2004 10:50:07 +0100

"Jean-Marc Vanel" <jmvanel@nospam.free.fr.removethis> schrieb im
Newsbeitrag news:41BB00A9.90406@nospam.free.fr.removethis...
> Robert Klemme wrote:
> > "Jean-Marc Vanel" <jmvanel@nospam.free.fr.removethis> schrieb im
> > Newsbeitrag news:Qh%td.2924$Of5.1971@nntpserver.swip.net...
> >
> >>Hello
> >>
> >>I want to federate (aggregate) several physical datasources, each
having
> >>its JDBC driver.
> >>
> >>My idea is that this aggregator could be implemented as a special JDBC
> >>driver or Connection
> ........
>
> > Basically you'll be implementing a complete database system in your
> > driver, especially since you have to support transaction semantics
etc.
> > What do you do with DDL for example? How will you specify in which db
a
> > new table will be created etc.? Also creating joins from huge tables
in
> > memory will be difficult to handle for the VM and it could be quite
> > imperformant. Are you sure you want that?
>
> I'm afraid you're right, if one want to stick to the JDBC spec. for a
> driver. In fact my aim would be to replace the feature "federated data
> server" of DB2II. And it's true that it's built on top of DB2, a full
> featured database. I guess I should look at federation feature in
> open-source databases such as MySQL, PostGreSQL, but this is outside the
> scope of this newsgroup.
>
> I found these two open-source Java frameworks that seem interesting.
> Daffodil might do what I want, but the configuration seems complicated.
>
> Daffodil Replicator Daffodil Replicator is a powerful Open Source data
> replication tool that allows bi-directional data synchronization between
> heterogeneous databases – Oracle, SQL Server, Postgre SQL, Derby,
> Daffodil DB – supporting JDBC drivers, triggers and procedures.

It can even replicate it's name in newsgroup postings. :-)

That will actually move data around and thus make it possible that a
single db does the join.

> C-JDBC - Clustered JDBC gives your applications a transparent (no code
> modification) access to a cluster of databases even if your database
> engines are not cluster-aware.

Thanks for that hint! That's interesting. Although, from quick glancing
at the web site I'd say that all these databases must be schema
compatible. I.e. the main point of C-JDBC is to route queries to
different servers (although they can be different makes), but not to join
results from different sources.

Both products do not seem to meet your requirements perfectly but, yes,
they could help, especially Replicator.

Kind regards

    robert

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