Use these tips to help you determine if a JDBC Data Mediator Service
suits the requirements of your application serving environment.
Miscellaneous database limitations
- Sybase before Version 12.5.1 does not support in-line queries in the “from”
clause, and therefore does not support multiple table DataGraphs with filters.
To use the Service Data Object in WebSphere® Application Server use Sybase
Version 12.5.1.
- The Informix® Dynamic
Server does not support sub-selects, which are needed for multiple table graphs.
Use Informix Extended
Parallel Server.
- Oracle 8i does not support the ANSI join syntax. The mediator in multiple
table cases requires Oracle 9i or 10g.
General performance recommendations
- Evaluate if your target projects are well suited to these technologies.
In general, projects that are read-intensive and require disconnected data
are good candidates.
- Limit the number of tables in the metadata. One or two is best because
relationships, with respect to filters, become ambiguous when graphs have
many branches.
- Work with small data sets as often as possible to avoid consuming excessive
amounts of memory within your applications. You can limit the amount of data
returned to the SDO by specifying filters in the metadata objects or by using
paging.
- For Web applications, if the DataGraph is not too large and is to be reused
later, store it in the user session.