Thursday, April 3, 2008


This is to inform the list that a demo has been put up which implements a basic and optimised version of the example query:

Select postal_code, count(patients) from global_db where diagnosis = 'X' order by count
where global_db

is a federation of two databases. In this case, the databases are the split version of the OpenMRS demo data with dummy post codes.

The demo is accessed through JSP pages which will return the results as an HTML page. The JSP page is based around an OGSA-DAI client program. This is to allow users with OGSA-DAI client libraries to access the demo at this stage.

The basic version of the example query operates without any optimisation to manage the amount of data transfered by the database resources and OGSA-DAI. The optimised version uses optimisations on the OGSA-DAI query plan to push operations to the databases to reduce the amount of data transfer needed but still retain the ability to do federated queries on multiple resources using OGSA-DAI and will allow different database schemas to be used. The demo is setup as JSP pages,


This are available for use now. If the URLs do not work, it is possible the OGSA-DAI instance is down for updating or maintenance. An email will be sent when the URLs are removed from use permenantly.

If possible, could a more realistic data set be made available which can be integrated into the demo and used for further development.

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