Time and Relational Theory, 2nd Edition

Appendix E

Implementation Considerations

This appendix discusses in some detail what’s involved in efficient implementation of the various “temporal” operators introduced in the body of the book. Among other things, it presents a series of transformation laws for the crucial operators PACK and UNPACK, and it sketches the details of certain implementation algorithms for those operators. Those algorithms have the desirable property that it should never be necessary to materialize the result of an UNPACK operation in its entirety. The appendix also describes an intuitively attractive graphical representation for these operations. It then considers algorithms for efficient implementation of the various U_ algebraic operators (U_MINUS, etc.) and U_update ...