ddbicon.pngDefining Indices

Although multiple indices can be defined for multi-keyed MKEYED and C-ISAM file tables, only one index should be defined for DIRECT, SORT, or single-keyed MKEYED tables.

Although the initial index is the primary unique key of the file, DDBuilder can be used to define as many indices as needed. However, PRO/5 and TAOS limit multi-keyed MKEYED files to 16 keys and a total of 48 segments within those keys. A segment can consist of a single column or portion of a column.

Up to 16 indices can be defined for an MKEYED table. The total size of an index cannot exceed 120 bytes. Each index must contain one or more segments, but the table cannot contain more than 48 segments. Each segment can be made up of a single column or part of a column. The indices must appear within the first 1024 bytes of the record.

To define the index, or key structure for a table, do the following:

  1. In the tree view, select the desired index.

  2. Select the index segment to display the General Index properties page.

  3. Enter data into the appropriate fields (click a field to display its input instructions).