Indexes can slow down other processes. When the user updates an indexed column, OpenEdge updates all related indexes as well, and when the user creates or deletes a row, OpenEdge changes all the indexes for that table.
Define the indexes that your application requires, but avoid indexes that provide little benefit or are infrequently used. For example, unless you display data in a particular order frequently (such as by zip code), then sorting the data when you display it is more efficient than defining an index to do automatic sorting.
Indexes take up disk space.(See the Calculating index size)