When you run CDC sessions, session log and restart token file history is often useful for recovery situations. You can use these historical files to find previous restart points when data needs to be re-extracted.

By default, the PowerCenter Integration Service keeps a single session log for each workflow or session. Change the

Save session log for these runs

option in either the session or Session Configuration properties to specify the number or runs to keep the session logs. You can also change the

Save session log by

option to keep session logs by timestamp instead of number of runs.

PWXPC keeps a single pair of initialization and termination restart token files. In the source CDC connection, specify a value other than 0 or 1in the

Number of Runs to Keep RestartToken File

option to retain more than a single pair of files.

You can determine starting and ending restart points for each extraction by using historical copies of the restart token file. You need historical copies of the session logs to re-extract changes at any point in between the session start and end.

When PWXPC issues a real-time flush to commit data to the targets, it issues message PWXPC_10081. This message contains the restart tokens at that point in time:

To restart an extraction from a specific commit point, use the restart tokens in the appropriate 10081 message to populate the restart token file and cold start the CDC session. PWXPC passes the restart token file values to PowerExchange to extract the data from that point forward.