The information management system IMS/VS, Part II: Data base facilities
William C. Mcgee · IBM Systems Journal · 1977
IMS/VS provides the following two data structure classes: structures perceived by the installation data administrator (DA), and structures perceived by the application programmer (AP). The DA class is basically hierarchically organized but provides a logical relationship facility that avoids redundant data storage and permits the representation of many-to-many relations. The DA class also includes primary and secondary index structures. For implementing DA structures, a variety of implementation methods are provided, so that the user may select the methods giving the best performance for particular data bases. Implementation methods range from sequential storage to storage by randomizing algorithms, and even include the implementing of data bases in main storage. Facilities are provided for the definition and creation of data bases. Creation is governed primarily by user-written load programs, with utilities provided for the integration of data bases into groups. Reorganization and recovery facilities are also provided through a number of utility programs.