1. Cache Guide
  2. Methods for Transmitting Changes Between TimesTen and Oracle Databases
  3. Setting a Passthrough Level
  4. Considerations for Using Passthrough

Considerations for Using Passthrough

Passing through update operations to the Oracle database for processing is not recommended when issued on cache tables in an AWT or SWT cache group.

  • Committed changes on cache tables in an AWT cache group are automatically propagated to the cached Oracle Database tables in asynchronous fashion. However, passing through an update operation to the Oracle database for processing within the same transaction as the update on the cache table in the AWT cache group renders the propagate of the cache table update synchronous, which may have undesired results.

  • Committed changes on cache tables in an SWT cache group can result in self-deadlocks if, within the same transaction, updates on the same tables are passed through to the Oracle database for processing.

A PL/SQL block cannot be passed through to the Oracle database for processing. Also, you cannot pass through to Oracle Database for processing a reference to a stored procedure or function that is defined in the Oracle database but not in the TimesTen database.

For more information about how the PassThrough connection attribute setting determines which statements are performed in the TimesTen database and which are passed through to the Oracle database for processing and under what circumstances, see PassThrough in Oracle TimesTen In-Memory Database Reference.

Note:

The passthrough feature uses OCI to communicate with the Oracle database. The OCI diagnostic framework installs signal handlers that may impact signal handling that you use in your application. You can disable OCI signal handling by setting DIAG_SIGHANDLER_ENABLED=FALSE in the sqlnet.ora file. Refer to Fault Diagnosability in OCI in Oracle Call Interface Programmer's Guide.