Fast/Unload

Fast/Unload is a utility whose primary function is to quickly unload data from a Model 204 data file to one or more sequential data sets.

The Fast/Unload utility consists of several functional units. One unit is a data extraction facility which reads data from a Model 204 data file. Another unit is a compiler which converts a special data language (FUEL) to machine language. The generated machine language actually performs the output function. A third unit is a reporting facility which provides a job log and reports any special conditions or errors that might have occurred during a run.

Fast/Unload can either be invoked directly as a standalone load module or from a User Language program. When invoked as a standalone load module, Fast/Unload enqueues the data file in share mode unless explicitly requested otherwise. If the enqueue fails, Fast/Unload terminates with an error condition code. It is thus the file manager's job to ensure that when Fast/Unload is run as a standalone load module, Model 204 does not have the file to be unloaded locked in exclusive mode.

The Fast/Unload User Language Interface, purchased as a separate Fast/Unload option, allows one to invoke Fast/Unload from User Language, using the FastUnload or FastUnloadTask functions of the Recordset class, or using the $FunLoad function. With this approach, an application builds a set of records to be unloaded, using standard User Language statements; for example, you can reduce unload time by restricting the set of records using indexed Model 204 fields. The Fast/Unload load module runs in a subtask (or PST under CMS) of Model 204. With the Fast/Unload User Language Interface, the processing can be performed either synchronously or asynchronously. A system manager can cancel or examine Fast/Unload requests, and each user can perform the same functions on asynchronous requests that he or she initiated. To explore the details, see the components of the Fast/Unload User Language Interface.

The Fast/Unload User Language Interface also provides the ability to unload data from a Model 204 group. The standalone Fast/Unload load module can also unload a group of files, although without access to group definitions in Model 204.

The Fast/Unload documentation has yet to be converted to M204wiki pages; the reference manual and most recent release notes are still maintained in PDF format. However, there is a wishlist for Fast/Unload in M204wiki.