Use these tips to help you determine if a JDBC Data Mediator
Service suits the requirements of your application serving environment.
Driver requirements for using SDO
to access DB2 UDB for iSeries
Because
the SDO JDBC Mediator takes advantage of the ResultSetMetaData interface
in JDBC 2.0, it must use JDBC providers that are fully compliant with
that specification. Both the IBM® Developer Kit for Java JDBC driver (also known as the DB2® UDB
for iSeries® Native driver) and the IBM Toolbox
for Java JDBC driver meet this criteria for JDBC
access to DB2 UDB for iSeries.
For performance reasons, however, neither of these drivers have default
settings to return all the information that the mediator requires.
You must set a connection property on the JDBC provider or data source
that corresponds to each driver for it to return full ResultSetMetaData
data sets.
The property you use varies according to how your driver
implementation acquires database connections.
- If your driver gets connections through the DriverManager class,
set the JDBC provider URL property extended metadata to true: extended
metadata=true. In this scenario, both the IBM Developer
Kit for Java and IBM Toolbox
for Java JDBC drivers require the same setting on
the JDBC provider object.
- If your application acquires connections through a data source,
set a different custom property on the data source, depending on the
driver that you use:
- For the IBM Toolbox for Java JDBC
driver, set the custom property extendedMetaData to
true.
- For the IBM Developer Kit for Java JDBC
driver, set the custom property returnExtendedMetaData to
true.
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 10g or later.
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.