The following events trigger a condense cycle:

During the condense cycle, the Condense task reads the data written to the journal receivers for the registered tables of interest since the last condense cycle. PowerExchange Condense determines the point in the change stream from which to begin reading data based on the sequence and restart tokens. PowerExchange Condense stores the change data in full or partial condense files.

When one of the following events occur, the condense cycle ends:

When the condense cycle ends, PowerExchange Condense closes the current condense file, takes a checkpoint, and issues a message that identifies the point in the change stream to which it processed changes. PowerExchange Condense uses the number of checkpoint files that you specify in the CHKPT_NUM parameter of the CAPTPARM member on a rotational basis.

PowerExchange Condense also stores information about the closed condense file in the Condense Control Table (CDCT). The CDCT includes an entry for each closed condense file, including the registration tag names, UOW start and end times, condense file type, and number or records. During extraction processing, the PowerExchange Listener reads the CDCT file to determine the closed condense file from which to extract change data.

You can define the retention period for the CDCT file and the condense files in the COND_CDCT_RET_P parameter in the CAPTPARM member. PowerExchange Condense deletes files older than this retention period at initialization, during a file switch, or at shutdown.

If a PowerExchange Condense job fails, an error message is written to the i5/OS console.