Databases Reference
In-Depth Information
2
PART
AN INTRODUCTION TO
ASSERTED VERSIONING
Chapter Contents
3. The Origins of Asserted Versioning: Computer Science Research
51
4. The Origins of Asserted Versioning: The Best Practices
75
5. The Core Concepts of Asserted Versioning
95
6. Diagrams and Other Notations
119
7. The Basic Scenario
141
Part 1 provided the context for Asserted Versioning, a history
and a taxonomy of various ways in which temporal data has
been managed over the last several decades. Here in Part 2, we
introduce Asserted Versioning itself and prepare the way for
the detailed discussion in Part 3 of how Asserted Versioning
actually works.
In Chapter 3, we discuss the origins of Asserted Versioning in
computer science research. Based on the work of computer
scientists, we introduce the concepts of a clock tick and an
atomic clock tick, the latter of which, in their terminology, is
called a chronon. We go on to discuss the various ways in which
time periods are represented by pairs of dates or of timestamps,
since SQL does not directly support the concept of a time period.
There are only a finite number of ways that two time periods
can be situated, with respect to one another, along a common
