Functions of Reload

The Reload function of FPA efficiently reloads a single DEDB area. It can also concurrently reload multiple DEDB areas without impacting all areas of a database.

Specifically, the Reload function reloads multiple DEDB areas from the QSAM data sets. If necessary, a sort step and an analyze step can be included in the Reload process. Additionally, the Reload function has the following characteristics:

• It operates independently of the IMS control region. Hence, one or more areas of a multi-area database can be reloaded while the application continues to use the areas that are not included in the maintenance process. This feature can significantly increase application availability.
  Note: This requires specific control of area selection and application code capable of handling 'FH' status codes.
• It can concurrently process multiple database areas with no database contention. This concurrent processing capability significantly decreases the time that is required for database maintenance, and it further increases application availability.
• An empty area unloaded by the Unload or Change process is clearly identified with an information message. Then, during the Reload process, an output data set for this empty area is initialized with no segment to prevent troubles when IMS DB/DC gets access to the output data set. The Audit report also shows the empty DEDB area.
• During the Reload process, dependent segment twin chains that are abnormally long can be controlled by specifying the load control information so that the impact on other database records in the same RAP CI is minimized. This feature is implemented by placing a user-specified limit on the number of segment occurrences that are to be placed closed to their root segments.
• The new area and RAP values for the database record are determined during unload processing. This allows all records for an area to be written to the same output data set, avoids an extra pass of the file, and simplifies the Reload process.
• There are no source code modifications made to any user-written or IMS program or control block. Because IMS program integrity is maintained, new exposures are not introduced.
• The Reload process can reload segment data in one area into multi-area data sets (MADS).
• The Reload process can optionally check the consistency between the DBD information in the library that is specified on the IMSACB DD statement and the DBD information in the USR files that were created during the Unload process.