How Are Indexes Used to Maintain a Logical Record Order?
A logical record order can also be maintained using an index, or inverted list, as they are sometimes
called. An index is simply a table that cross-references record addresses with some field value. For example,
Figure H-8(a) shows the ENROLLMENT records stored in no particular order, and Figure H-8(b)
shows an index on StudentNumber. In this index, the StudentNumbers are arranged in sequence, with
each entry in the list pointing to a corresponding record in the original data.