Tuning parameters for data access resources
For better application performance, one can tune some data access resources through the WAS administrative console.
Tune these properties of data sources and connection pools to optimize the performance of transactions between your application and datastore.
Data source tuningTo view the administrative console
page where you configure the following properties, click Resources > JDBC Providers > JDBC_provider > Data sources > data_source > WAS connection properties.
- Enable JMS one phase optimization support
- If your application does not use JMS messaging, do not select this option. Activating this support enables the Java Message Service (JMS) to get optimized connections from the data source. Activating this support also prevents JDBC applications from obtaining connections from the data source. For further explanation of JMS one phase support, refer to the article entitled "Sharing connections to benefit from one phase commit optimization" in this information center.
- Statement cache size
- Number of prepared statements that are cached per connection. (A prepared statement is a precompiled SQL statement that is stored in a prepared statement object. This object is used to efficiently run the given SQL statement multiple times.) In general, the more statements your application has, the larger the cache should be. Be aware, however, that specifying a larger statement cache size than needed wastes application memory and does not improve performance.
Determine the value for your cache size by adding the number of uniquely prepared statements, callable statements (as determined by the SQL string, concurrency, and the scroll type) for each application that uses this data source on a particular server. This value is the maximum number of possible prepared statements that are cached on a given connection over the life of the server. Additional information about this setting...
Default: For most databases the default is 10. Zero means there is no cache statement.
Connection pool tuningTo view the administrative console
page where you configure the following properties, click Resources > JDBC Providers > JDBC_provider > Data sources > data_source > Connection pool settings.
- Maximum connections
- Specifies the maximum number of physical connections that can be created in this pool. These are the physical connections to the backend datastore. When this number is reached, no new physical connections are created; requestors must wait until a physical connection that is currently in use is returned to the pool.
For optimal performance, set the value for the connection pool lower than the value for the Web container threadpool size. Lower settings, such as 10 to 30 connections, might perform better than higher settings, such as 100. Additional information about this and related settings...
Default: 10
- Minimum connections
- Specifies the minimum number of physical connections to maintain. Until this number is exceeded, the pool maintenance thread does not discard physical connections.
If you set this property for a higher number of connections than your application ultimately uses at run time, you do not waste application resources. WebSphere Application Server does not create additional connections to achieve your minimum setting. Of course, if your application requires more connections than the value you set for this property, application performance diminishes as connection requests wait for fulfillment. Additional information about this and related settings...
Default: 1