Neon Enterprise Software, Inc.

Wayne E Fisher

A method of ensuring that an IMS database and its description are synchronized. A copy of the description used to load the database is stored and maintained within said database. Before the database is accessed, a copy of the description is compared with another copy of the description stored in a data management block. A determination is then made as to whether the copy of the description in the database and the copy of the description in the data management block are synchronized. Responsive action, such as alerting the user to a problem with the description, may occur if the database descriptions are not synchronized.

Ensuring that a database and its description are synchronized

Space within an IMS database can be managed during loading or updating of the database. After an IMS database is loaded, a space management program can assume control from the IMS program for a period of time. During this period of time, the space management program obtains memory addresses of IMS control blocks built by the IMS program and further obtains information about the IMS database. When the IMS program attempts to insert data into the IMS database, either during loading or updating of the database, the space management program reassumes control from the IMS program. The space management program selects a storage location for the data to be stored, and modifies the IMS control blocks to indicate the storage location selected. The space management program may also insert the data into the storage locations selected. Control is then passed back to the IMS program. If segments are to be inserted into the IMS database, and such segments are to be split, then the space management program selects two storage locations for the components of the split segment to be stored. The storage locations selected by the space management program are selected based on IMS database user preferences.

Space management of an IMS database

An index can be maintained during a reorganization of data in a database by retaining each root segment, or the prefix component of each root segment, in its storage location during the reorganization. Correction of an index after a reorganization of data in a database can be facilitated by assigning a unique token to each target segment, or the prefix component of each target segment, and each corresponding index entry having an address to a target segment, prior to a reorganization of data. The unique token for a given target segment, or the prefix component for a given target segment, and the unique token for a corresponding index entry are the same. After a reorganization of data in the database, the unique token of a first index entry is read. Then, the unique token of each target segment, or the prefix component of each target segment, is read until a match is found.

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Sugar Land, TX, United States of America

Wayne E Fisher