Point-in-time change accumulation overview
Point-in-time change accumulation (PITCA) merges all available updates from different systems into a single file.
The PITCA file contains all completed transactions up to the specified point in time. For example, if two systems are sharing a database, logs for both systems must be archived for the specified point in time. The PITCA file will be within the time stamp range of the input logs.
Because PITCA files contain only complete transactions, the accumulation process cannot continue beyond the PITCA end time. When you use PITCA for recovery purposes, you must perform and record an image copy in the RECON to create a valid starting point for subsequent change accumulation processing.
Differences with standard change accumulation
The standard change accumulation process maintains a transitional view of a database that is represented in the IMS log data. The accumulation file that is generated by standard change accumulation processing includes records of completed transactions. The accumulation file also includes partially completed transactions and a subset of records of the complete update. These partially completed transactions and subsets of records are recorded in the change accumulation file as spill records.