Selecting an unload utility for your use
IMS High Performance Unload provides two unload utilities, FABHURG1 and FABHFSU, both of which run as HSSR application programs. Before selecting which utility to use, you must understand the functional differences between each utility.
The FABHURG1 utility is relatively simple. The FABHFSU utility provides more functions than FABHURG1, and is compatible with FSU II.
Both unload utilities are usually run in the ULU region. In that ULU region, all database segment types are unloaded automatically. These utilities can also be run in DLI region, and FABHURG1 can be run in the DBB region.
- Unload a database into one of the six standard formats.
- One of the six standard formats is acceptable as input to IMS HD Reorganization Reload utility
or a compatible utility. For input processing by application programs,
the other four standard formats are more practical. The six standard
formats include the communication industry standard format (*CS format).Note: The *CS format cannot be selected in FABHFSU jobs.
- Do a migration unload to HALDB or a fallback unload from HALDB.
- FABHURG1 can unload a database to migrate an HIDAM
or HDAM database to a PHIDAM database or a PHDAM database. FABHURG1
can also unload a database to do fallback from a PHIDAM or PHDAM database
to an HIDAM or HDAM database. The unloaded data set created is compatible
with the unloaded data set created by IMS HD
Reorganization Unload utility. Note: You can also use FABHFSU in PSF mode to do a migration unload. By using FABHFSU in PSF mode, you can process the partitions in parallel, which results in faster processing. For more information, see Parallel migration unload. Fallback unload from HALDB is not supported by FABHFSU.
- Create a database extract to perform database tuning experiments.
- Using the exit routine FABHEXTR provided by IBM®, you can create a small database extract from a large database, for use in database tuning experiments.
- Use a user record-formatting routine to format output records or to edit segment data (for system programmers).
- FABHURG1 accepts a user exit that enables system programmers to
write a user record-formatting routine for formatting output records
and an optional exit routine for editing segment data.Note: User exit that enables system programmers to write a user record-formatting routine for formatting output records or optional exit routines for editing segment data are not supported by FABHFSU.
- Create up to three data sets in one single execution.
- Different record formats can be specified for each output data
set. If FABHFSU runs in the DLI region, different PCBs that refer
to the same DBD can be specified for each output data set. Note: FABHURG1 does not support generating multiple outputs with different formats.
- Use a user exit that is compatible with user exit of IPR Unload utility or DBT HSSR (for application programmers).
- The user exit is compatible with the user exit of FABHFSU in DBT HSSR and with the user exit of IPR Unload. A different user exit routine can be specified for each output.
- If you want to edit segment data or to discard some segments on
the basis of criteria you chose, you should use FABHFSU and write
an exit routine for it.Notes:
- User exits are also provided for FABHURG1, but they are intended to be used mainly by system programmers who have good knowledge of IMS database and HSSR Engine.
- FABHURG1 does not support user exits that are compatible with user exits of IPR Unload utility.
- Unload a specified range or portion of an HISAM, HIDAM, or HDAM database.
- You can unload the portion of the database to be read. For HISAM or HIDAM, the limits of the range are specified as keys. For HDAM, the limits of the range are defined as relative block numbers of the CIs or blocks in the Root Addressable Area.
- Unload a multivolume database by scanning separately or concurrently (PSF mode).
- FABHFSU has two different modes: the standard mode and the Parallel
Scan Facility (PSF) mode. In the PSF mode, FABHFSU performs individual
scan phases, which can run separately or concurrently to unload a
multivolume database. Note: In both the standard mode and the PSF mode, FABHFSU runs as an HSSR application program.
- Use FSU II JCL.
- You can use your FSU II JCL to run FABHFSU by making small modifications
to your FSU II JCL.Note: FABHURG1 is not compatible with FSU II.