Fast path is an optional feature of IMS that is specifically designed for certain types of on-line system. The fast path feature is available only with IMS DC, not with IMS batch or DL/I with CICS. The processing carried out on behalf of one input message to is called a transaction.
Although individual transactions themselves may be very simple, the system may be required to handle a very high transaction rate, say several thousand transactions a minute. The Fast Path feature is intended for applications having high transaction rate, comparatively simple database processing.
The fast path feature provides both special data communications facilities and two special data base structures, the Main Storage database (MSDB) and the Data Entry database (DEDB). Main storage and data entry databases have a simpler structure than other IMS databases and provide better performance for certain kinds of operation.
Data entry database is a restricted form of hierarchy that is kept on secondary storage in the usual way but is partitioned into area for enhanced availability and other reasons.
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