WebSphere Application Server data source properties

Use this page to set advanced properties for your data source. These properties activate and configure services that the application server applies to data sources to customize how connections are used within the application server. These properties do not affect how connections are used by the database.

You can access this administrative console page in several ways:

Configuration tab

Statement cache size

Specifies the number of statements that can be cached per connection. WebSphere Application Server caches a statement after the user closes it.

The WebSphere Application Server data source optimizes the processing of prepared statements and callable statements by caching those statements that are not being used in an active connection. Both statement types help maximize the performance of transactions between your application and datastore.
  • A prepared statement is a precompiled SQL statement that is stored in a PreparedStatement object. Application Server uses this object to run the SQL statement multiple times, as required by your application run time, with values that are determined by the run time.
  • A callable statement is an SQL statement that contains a call to a stored procedure, which is a series of precompiled statements that perform a task and return a result. The statement is stored in the CallableStatement object. Application Server uses this object to run a stored procedure multiple times, as required by your application run time, with values that are determined by the run time.
If the statement cache is not large enough, useful entries are discarded to make room for new entries. To determine the largest value for your cache size to avoid any cache discards, add the number of uniquely prepared statements and 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 statements that can be cached on a given connection over the life of the server. Setting the cache size to this value means you never have cache discards. In general, the more statements your application has, the larger the cache should be.
Note: This statement cache size setting is different from WebSphere Application Server V4.0.x. In V4.0.x, the maximum number of possible prepared statements is cached for the data source within an application server. In V5 and later versions, statement cache size is defined on a given physical connection.

You can also use the Tivoli Performance Viewer to minimize cache discards. Use a standard workload that represents a typical number of incoming client requests, use a fixed number of iterations, and use a standard set of configuration settings. Note: The higher the statement cache, the more system resources are delayed. Therefore, if you set the number too high, you could lack resources because your system is not able to open that many prepared statements.

In test applications, tuning the statement cache improved throughput by 10-20%. However, because of potential resource limitations, this might not always be possible.

Data type Integer
Default Depends on the database. Most are 10. Informix versions 7.3, 9.2, 9.3, and 9.4, without the respective latest fixes, must be 0. A default of 0 means there is no cache statement.

Enable multithreaded access detection

If checked, the following warning message is entered in the WebSphere Application Server system out log if multiple threads attempt to concurrently use the same connection handle. You can use this property to debug connection problems if you think the problems might be caused by multiple threads trying to use the same connection handle. Having multiple threads concurrently using the same connection handle is a programming model violation.

J2CA0167W: An attempt to concurrently use the same connection handle by multiple threads has been detected. The connection handle is: {0}.

Enable database reauthentication

If checked, there cannot be an exact match on connections retrieved out of the WebSphere Application Server connection pool (that is, connection pool search criteria do not include user name and password). Instead, the reauthentication of connection is done in the doConnectionSetupPerTransaction() of the DataStoreHelper class. Note that WebSphere Application Server runtime does NOT provide connection reauthentication implementation. Therefore, when this box is checked you MUST extend the DataStoreHelper class to provide implementation of the doConnectionSetupPerTransaction() method where the reauthentication takes place. Failure to do that results in wrong connections being handed out to users. For more information, refer to the API documentation for com.ibm.websphere.rsadapter.DataStoreHelper#doConnectionSetupPerTransaction(...).

Connection reauthentication can help improve performance by reducing the overhead of opening and closing connections, particularly for applications that always request connections with different user names and passwords.

Enable JMS one-phase optimization support

If checked, the application server allows JMS to get optimized connections from this data source. This property prevents JDBC applications from sharing connections with CMP applications.

Manage cached handles

Specifies whether the container tracks cached handles, which are connection handles that an application component holds active across transaction and method boundaries. You can use this property to debug connection problems, but tracking handles can cause large performance overhead during run time.

Log missing transaction context

Specifies whether the container issues an entry to the activity log when an application obtains a connection without a transaction context. These are exceptions to the J2EE programming model connection requirements.

Pretest existing pooled connections

Specifies whether the connection manager tests the validity of pooled connections before returning them to applications. If you select this option, you can specify how often, in seconds, the connection manager retries the connection if the initial attempt fails.

Retry interval

If you select the Pretest existing pooled connections option, you can use the Retry interval field to specify the frequency, in seconds, that the connection manager retries the existing pooled connection, if the initial attempt fails.

Data type Integer

Pretest new connections

Specifies whether the connection manager tests the validity of the initial connection to a database. If you select this option, you can specify the number of times that the connection manager retries the connection and the amount of time the connection manager waits between retries.

Number of retries

If you select the Pretest new connections option, you can use the Number of retries field to specify the number of times to retry the initial connection, if the first attempt fails.

Data type Integer

Retry interval

If you select the Pretest new connections option, you can use the Retry interval field to specify the frequency, in seconds, that the connection manager retries the initial connection to a database, if the first attempt fails.

Data type Integer

Pretest SQL string

Specifies the SQL statement that the application server sends to the database to test an existing pooled connection or a new connection to a database. Because the pretest operation is designed to test only that a connection makes a round trip to and from the database server, use a simple, low-impact query. A good choice for a PreTest SQL string is a generic query that has minimal potential impact on performance of the application server.

Data type String



Related concepts
Resource adapters
JDBC providers
Data sources
Related tasks
Configuring a data source using the administrative console
Configuring connection factories for resource adapters within applications
Configuring J2EE Connector connection factories in the administrative console
Related reference
Custom property settings
Reference topic Reference topic    

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Last updatedLast updated: Aug 30, 2013 4:53:43 PM CDT
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