|From:||Juan Sequeda <jsequeda@xxxxxxxxxxxxx>|
|Date:||Thu, 12 Sep 2013 09:31:16 -0500|
On Thu, Sep 12, 2013 at 8:33 AM, John F Sowa <sowa@xxxxxxxxxxx> wrote:
So what is the definition of legacy system?
In my (short) experience, talking to real businesses and customers, many people consider RDBMSs as legacy systems.
All in all, people want to bridge a previous technology (RDBMS) with new technology (Semweb).
There are two modes of operation. ETL or Wrappers.
With ETL, you have (if I understand correctly), what you are calling "batch processing". With wrappers, the data doesn't move. It continues to be in the RDBMS, and can be queried by SQL and SPARQL.
Our system, Ultrawrap, takes full advantage of the SQL infrastructure. We push down SPARQL optimization to the SQL optimizer. The result: the RDBMS successfully optimizes SPARQL and query execution of SPARQL vs SQL are comparable and sometimes equal.
I agree. See above.
I agree. See above.
I completely agree! And actually, it has been proven that SPARQL and non-recursive safe Datalog with negation have equivalent expressive power. Therefore, by classical results, SPARQL is equivalent from an expressive point of view to Relational Algebra (SQL).
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