SAS/ACCESS Interface to SYSTEM 2000 Data Management Software: Reference

SYSTEM 2000 Indexing

One of the specifications when defining a schema item is whether SYSTEM 2000 software is to create an index of its values. The software uses the indexes to access the appropriate data records quickly and efficiently.

A schema item for which an index is created is a key item, implying that it provides easy access to data records containing its values. Thus, a key item has an associated index of every distinct value that occurs for the schema item. Note, however, that key values do not have to be unique, and there can be many key items in a database definition or none.

If a schema item is defined as non-key, its values are not indexed, although they can be searched sequentially.

In addition, you can create or delete an index of values by using the SYSTEM 2000 CREATE INDEX and REMOVE INDEX statements. The software automatically changes the specified item to key or non-key. (For information on these statements, see the appropriate SYSTEM 2000 documentation.)

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