Index question

Suppose we have a header record, with a "closed date" field, and a detail record with a "vendor" field.

Both files are DDS-created PFs, and the detail file has a LF indexed on its "parent" field, so it's easy enough to go back and forth between parent and child.

Now suppose we are doing an SQL SELECT on a join of the header and the detail, with a WHERE clause involving both fields.

Is there a way to set up an index, whether from SQL or via a new DDS LF, that would speed up this SELECT?

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JHHL