Processing Fast Path databases

Using EXEC DLI commands under DBCTL, a CICS® program or a batch-oriented BMP program can access DEDBs. Parameters allow your program to use facilities of the DEDBs such as subset pointers.

A DEDB contains a root segment and as many as 127 types of dependent segment. One of these types can be a sequential dependent; the other 126 are direct dependents. Sequential dependent segments are stored in chronological order. Direct dependent segments are stored hierarchically.

DEDBs provide high data availability. Each DEDB can be partitioned, or divided into multiple areas. Each area contains a different set of database records. In addition, you can make up to seven copies of each area data set. If an error exists in one copy of an area, application programs can access the data by using another copy of that area. This is transparent to the application program. When an error occurs to data in a DEDB, IMS does not stop the database. It makes the data in error unavailable, but continues to schedule and process application programs. Programs that do not need the data in error are unaffected.

DEDBs can be shared among application programs in separate IMS systems. Sharing DEDBs is virtually the same as sharing full-function databases, and most of the same rules apply. IMS systems can share DEDBs at the area level (instead of at the database level as with full-function databases), or at the block level.