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In-Depth Information
bi-temporal data. Of course, with two organizing principles—
four levels of granularity, and the non/uni/bi distinction—the
result would be a matrix rather than a hierarchy. In this case, it
would be a matrix of 12 cells. Indeed, in places in Chapter 1, this
alternative organization of temporal data management methods
seems to peek out from between the lines. However, we believe
that the taxonomy we are about to develop will bring out the
similarities and differences among various methods of managing
temporal data better than that matrix; and so, from this point
forward, we will focus on the taxonomy.
The Root Node of the Taxonomy
The root node of a taxonomy defines the scope and limits of
what the taxonomy is about. Our root node says that our taxon-
omy is about methods for managing temporal data. Temporal
data is data about, not just how things are right now, but also
about how things used to be and how things will become or
might become, and also about what we said things were like
and when we said it. Our full taxonomy for temporal data man-
agement is shown in
Figure 2.2
.
The two nodes which partition temporal data management
are reconstructable data and queryable data. Reconstructable
data is the node under which we classify all methods of manag-
ing temporal data that require manipulation of the data before it
can be queried. Queryable data is the opposite.
Temporal Data Management
Reconstructable Temporal Data
Queryable Temporal Data
Event Temporal Data
State Temporal Data
Uni-Temporal Data
Bi-Temporal Data
The Alternative
Temporal Model
Temporal Data
Best Practices
The Standard
Temporal Model
The Asserted Versioning
Temporal Model
Figure 2.2 A Taxonomy of Temporal Data Management Methods.
