Recovering Sessions in Informatica

If you stop a session or if an error causes a session to stop, refer to the session and error logs to determine the cause of failure. Correct the errors, and then complete the session. The method you use to complete the session depends on the properties of the mapping, session, and Informatica Server configuration.

Use one of the following methods to complete the session:

• Run the session again if the Informatica Server has not issued a commit.
• Truncate the target tables and run the session again if the session is not recoverable.
• Consider performing recovery if the Informatica Server has issued at least one commit.

When the Informatica Server starts a recovery session, it reads the OPB_SRVR_RECOVERY table and notes the row ID of the last row committed to the target database. The Informatica Server then reads all sources again and starts processing from the next row ID. For example, if the Informatica Server commits 10,000 rows before the session fails, when you run recovery, the Informatica Server bypasses the rows up to 10,000 and starts loading with row 10,001. The commit point may be different for source- and target-based commits.

By default, Perform Recovery is disabled in the Informatica Server setup. You must enable Recovery in the Informatica Server setup before you run a session so the Informatica Server can create and/or write entries in the OPB_SRVR_RECOVERY table.

Causes for Session Failure

• Reader errors. Errors encountered by the Informatica Server while reading the source database or source files. Reader threshold errors can include alignment errors while running a session in Unicode mode.
• Writer errors. Errors encountered by the Informatica Server while writing to the target database or target files. Writer threshold errors can include key constraint violations, loading nulls into a not null field, and database trigger responses.
• Transformation errors. Errors encountered by the Informatica Server while transforming data. Transformation threshold errors can include conversion errors, and any condition set up as an ERROR, such as null input.

Fatal Error

A fatal error occurs when the Informatica Server cannot access the source, target, or repository. This can include loss of connection or target database errors, such as lack of database space to load data. If the session uses a Normalizer or Sequence Generator transformation, the Informatica Server cannot update the sequence values in the repository, and a fatal error occurs.