Progress
Database Design
Guide
Case 1: WHERE searchExpr
If there is an index on the field in searchExpr, or if field is the first component in a multi-field index, Progress uses the index. Otherwise, Progress uses the primary index:
If the searchExpr references a word-indexed field, Progress uses the word index.
If there is a BY field clause, and field is indexed, Progress uses the index to sort returned records as long as there is no index on the WHERE clause. If field is not indexed, Progress creates a temporary sort table and sorts the records at run time.
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