Re: federate several datasources

From: Robert Klemme (bob.news_at_gmx.net)
Date: 12/10/04

  • Next message: john martin: "Advice on persistent storage in Java" 
    Date: Fri, 10 Dec 2004 14:11:11 +0100

    "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, that will respond to queries from the application
    > by dispatching to the relevant tables in each physical database, and
    > construct the final rowset by assembling rowsets from each physical
    > database.
    >
    > JDBCAggregator aggregator = new JDBCAggregator();
    > aggregator.addConnection(db1);
    > aggregator.addConnection(db2);
    > ResultSet = aggregator.createStatement().executeQuery (
    > "SELECT * from db1.client as cl, db2.order as ord " +
    > "where cl.id = ord.client_id" );
    >
    > where all tables from database 1 (respectively 2) get prefix db1 (resp.
    > db2). Or possibly no prefix if there is no ambiguity.
    >
    > I'm looking for an open source project or code suggestions.

    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?

    Kind regards

        robert

  • Next message: john martin: "Advice on persistent storage in Java"

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