Advantage Concepts
If the key being Seeked is within the index scope or record filter boundaries (the ‘Nelson’ key, for instance), then index scope and record filter performance is identical.
If the key being Seeked is before the top index scope or record filter boundary (the ‘Brown’ key, for instance), index scopes are much faster than traditional record filters. With index scopes, a Seek to the top of the scope (the first ‘Jones’ key) or an immediate repositioning to the end of file will occur, depending if Softseek is set. With traditional record filters, a series of skips will be performed (from the ‘Brown’ key to the ‘Jones’ key) before the Softseek setting is accounted for.
If the key being Seeked is after the bottom index scope or record filter boundary (the ‘Smith’ key, for instance), then index scopes are once again faster than traditional record filters. With index scopes, an immediate repositioning to the end of file will occur. With record filters, a series of skips will be performed (starting at the ‘Smith’ key) until the end of file is reached.