Transaction Log Truncation

Replication Agent supports both automatic and manual log truncation.

Replication Agent provides two options for automatic transaction log truncation:

Periodic truncation, based on a time interval you specify
Automatic truncation whenever Replication Agent receives a new LTM locator value from the primary Replication Server. You also have the option to switch off automatic log truncation. By default, automatic log truncation is enabled and is set to truncate the log whenever Replication Agent receives a new LTM locator value from the primary Replication Server.

To configure Replication Agent log truncation, observe these guidelines:

When pdb_include_archives is set to true, the default, and pdb_archive_remove is set false, the Replication Agent does not perform any online or archived transaction log truncation. When pdb_include_archives is set to true, the default, and pdb_archive_remove is set to true, Replication Agent deletes from the pdb_archive_path location the archive redo logs that have already been processed. The Replication Agent is not responsible for archiving online transaction logs.

Note: Sybase recommends that you configure the Replication Agent to remove archive log files only if an additional archive log directory is used.
When the configuration parameter pdb_include_archives is set to false, Replication Agent performs online redo log truncation (either scheduled or manual) by issuing the alter system command with the archive log sequence keywords. The command uses the log sequence number of the redo log file whose contents have been processed by the Replication Agent and are ready to be archived.

Note: The alter system command syntax in Oracle allows redo log files to be archived in addition to the single log sequence specified in the command. To avoid unintentional archiving, Replication Agent issues this command only when it is processing the redo log file whose status is current.
You can specify the automatic truncation option you want (including none) by using ra_config to set the value of the truncation_type configuration parameter.

To truncate the transaction log automatically based on a time interval, use ra_config to set the value of the truncation_interval configuration parameter.
You can truncate the Replication Agent transaction log manually, at any time, by invoking pdb_truncate_xlog at the Replication Agent administration port.

For more information on these properties, see the Replication Agent Reference Manual. For a more detailed description of truncating, see "Administering Replication Agent” in the Replication Agent Administration Guide.