DB Scan function
The DB Scan function is a functional replacement for the IMS Database Scan utility.
When you run the DB Scan function, the OS/VS Initiator loads the batch region controller (DFSRRC00). The region controller loads and transfers control to the Unload function. You can use DB Scan any time that you run the Unload function as an independent utility.
When the Unload function receives control, it determines the values to use for the user-controlled options as explained in How-the-utilities-build-options. The Unload function then builds control blocks, opens data sets, and begins to scan the database.
The Unload function retrieves input segments from the database and builds the appropriate work file 1 records. It uses standard OS/VS access methods rather than DL/I to scan the database.
When the Unload function scans the database, it accumulates various statistics (for example, segment placement information and database record sizes). At the end of the scan, the Unload function closes the data sets and generates the statistical reports. If you provide a PDX data set, the information for the reports is also stored in the PDX. You can view or print the reports at any time using the ISPF interface.
The Unload function works with DBRC in the same way as the IMS Database Scan utility does.
Figure 1 shows the general system flow when you run the DB Scan function.
Figure 1. System flow of the DB Scan function
