An index, or keyed sequence access path, provides access to a table that is arranged according to the contents of key columns. The keyed sequence is the order in which rows are retrieved. The access path is automatically maintained whenever rows are added to or deleted from the table, or whenever the contents of the index columns are changed. The best examples of an index is an index that is created with the CREATE INDEX statement, or a logical file that is created with the CRTLF command.
Columns that are good candidates for creating indexes are: