FAST AND ROBUST OPTIMIZATION OF COMPLEX DATABASE QUERIES

A robust way is described for optimizing complex data base queries while retaining the optimization speed of heuristic methods. The heuristic join-sequencing algorithm is modified to permit any of, or a combination of: (1) multiple passes of the heuristic algorithm, each with a different metric, producing multiple plans; (2) complex combinations of the criteria by which such heuristics make their choices; and/or (3) backtracking to consider alternatives to any particular decision in the sequence.