Practical hardware for linear execution of relational database operations

0 Introduction It may be useful, in doing a natural join of two database relations (or some other operation such as intersection, union or projection) to calculate first a bit array showing which tuples from each relation participate in the result. Table i gives an example of a relation of 6 tuples joined with a relation of 5 tuples. Only the join attributes are shown. The values are in no particular order and duplicates appear because the join attribute is not necessarily the key of either relation: the values of other attributes are assumed to be such that each tuple is unique. The table entry is 1 wherever a match occurs and 0 elsewhere.