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:

Sample WHERE Clause
Indexes Used
WHERE Customer.Name BEGINS "B" 
Name
WHERE Customer.Postal-Code BEGINS "01" 
Cust-Num (primary)

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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