Running the Resync function

Use the Resync function to synchronize index pointer segments that are in secondary index databases with the pointers that are in the primary DEDB database. FPA runs the Resync function as a standard z/OS® batch job. You must specify an EXEC statement and DD statements that define the input and output data sets in your JCL.

Considerations before running a Resync job:
  • With online synchronization, if the DEDB is updated while the secondary index databases are being updated, the DEDB and the secondary index databases might be out of synchronization after the job. In such a case, run the Resync job again to synchronize the databases.
  • Only the direct update method and offline synchronization support secondary index databases that contain non-unique keys. If the secondary index databases contain non-unique keys, use the direct update method or offline synchronization.

Three methods to synchronize secondary index databases

The Resync function supports three methods for synchronizing secondary index databases. Each method involves running one or more Resync jobs in corresponding Resync modes, which are controlled by the RESYNCMODE keyword of the INDEXBLD command.

For online synchronization, the following three methods are supported. For offline synchronization, only the verify update method is supported.

Verify update method (RESYNCMODE=VERIFYUPDATE)
The Resync function scans the DEDB areas and their secondary index databases to identify out-of-sync pointers in the secondary index databases. Then to update the secondary index databases, the function inserts and deletes the identified pointer segments. This method involves the following processes:
  1. Area scan process: Scans the DEDB areas and generates records in the unverified resync pointer segment record data sets.
  2. Sort process: Starts DFSORT and sorts the records in the unverified resync pointer segment record data sets.
  3. Verify update process: Scans the secondary index databases, compares the pointer segment records in the secondary index databases to the records in the unverified resync pointer segment record data sets, and updates the secondary index databases.
By default, the Resync function runs the three processes in one job. However, if you use online synchronization, you can separate the area scan process and the sort process into different jobs. For the area scan process, you must use the Resync function. For the sort process, you can use DFSORT or a functionally equivalent sort program.
Direct update method (RESYNCMODE=DIRECTUPDATE)
The Resync function scans only the DEDB areas and inserts all pointer segments into the secondary index databases. The Resync function does not scan the secondary index databases because it assumes that the secondary index databases are empty or do not contain any index segments for the scanned DEDB areas. This method involves the following processes:
  1. Area scan process: Scans the DEDB areas and generates records in the unverified resync pointer segment record data sets.
  2. Direct update process: Reads the unverified resync pointer segment records and updates the secondary index databases.
The Resync function runs both processes in one job. However, you can separate the area scan process into a different Resync job.
Two-step method (RESYNCMODE=VERIFY and RESYNCMODE=UPDATE)
Using this method, you run two Resync jobs. The first job (verify step) scans the DEDB areas and their secondary index databases, and the second job (update step) updates the secondary index databases.
  1. Verify step: Scans the DEDB areas and their secondary index databases, generates intermediate pointer segment records, uses DFSORT to sort the records, and identifies out-of-sync pointers. The records are stored in the resync pointer segment record data sets and used in the subsequent update step.
  2. Update step: Reads the out-of-sync pointers in the resync pointer segment records, and updates the secondary index databases.
Figure 1. Resync methods
This figure shows the three main methods for synchronizing secondary index databases with the Resync function. Details about these methods are described in this topic.