Database types and functions
IMS™ databases come in two general classes: full-function and Fast Path. Each class includes different types of databases and each database type can have different functions and characteristics.
- Summary of IMS database types and functions
The following table provides a summary of characteristics, functions, and options of the different types of IMS databases. - Full-function database types
IMS full-function databases are hierarchical databases that are accessed through DL/I calls. IMS makes it possible for application programs to retrieve, replace, delete, and add segments to IMS databases. - Fast Path database types
Fast Path databases include data entry databases (DEDBs) and main storage databases (MSDBs). DEDBs provide efficient storage for and access to large volumes of data. DEDBs also provide a high level of availability to that data. MSDBs store and provide access to an installation's most frequently used data. - Creating logical relationships
Logical relationships resolve conflicts in the way application programs need to view segments in the database. - Creating secondary indexes
Secondary indexes are indexes that process a segment type in a sequence other than the one that is defined by the segment's key. A secondary index can also process a segment type based on a qualification in a dependent segment. - Database versioning
When database versioning and the IMS catalog are enabled in an IMS system, you can maintain multiple different versions of a database. Application programs can access the older versions of the database without being changed, while the newer versions of the database can be changed to support new application program requirements. - Optional database functions
In addition to logical relationships and secondary indexes, which are described in separate topics, IMS databases support a variety of optional functions that you can choose to implement depending on the database type you are using and the needs of your installation. - XML storage in IMS databases
Because XML and IMS databases are both hierarchical, IMS is an effective database management system for managing XML documents.
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