The workflow system uses indexes to facilitate and speed up searches.
Before you can use a workflow field value in an index, you must add the corresponding database field to a workflow roster, queue, or event log. You cannot change or delete a mandatory system-defined index.
By default, the workflow system creates an index for user queues called PWDefaultOrder. This index determines the order in which work assigned to users appear in their inboxes. You can modify this index to change the default order.
Use more indexes sparingly because they affect the space and performance of the system. Indexes are the primary means of reducing disk I/O when properly used. Retrieval performance of indexed data remains almost constant, even as new rows are inserted. However, the presence of many indexes on a table decreases the performance of updates, deletes, and inserts because the system must also update the indexes that are associated with the table.
You can create simple or composite indexes. A composite index (also called a concatenated index) is an index that you create on multiple columns in a table. Columns in a composite index can appear in any order. Composite indexes can speed retrieval of data for search filters in which the filter conditions reference all or the leading portion of the columns in the composite index. Therefore, the order of the columns that are used in the definition is important; generally, the most commonly accessed or most selective columns go first.
To add an index: