Databases Reference
In-Depth Information
child version, and whose episode begin date is not later than the
effective begin date of the new version. In other words, it enables
us to do TRI checking from one parent-side row, rather than hav-
ing to go back and find the row that begins that parent episode.
This significantly improves performance for temporal referential
integrity checking.
The result of TRI enforcement is to guarantee that the effec-
tive-time extent of any version representing a TRI child object
completely [fills] the effective-time extent of one set of contigu-
ous versions representing a TRI parent object.
In addition, note that the presence of this redundant column
has little maintenance cost associated with it. As new versions
are added to an episode, the episode begin date of the previous
version is just copied onto that of the new version. Only in the
rare cases in which an episode's begin date is changed will this
redundancy require us to update all the versions in the episode.
Glossary References
Glossary entries whose definitions form strong inter-
dependencies are grouped together in the following list. The
same glossary entries may be grouped together in different ways
at the end of different chapters, each grouping reflecting the
semantic perspective of each chapter. There will usually be sev-
eral other, and often many other, glossary entries that are not
included in the list, and we recommend that the Glossary be
consulted whenever an unfamiliar term is encountered.
Allen relationships
contiguous
filled by
include
asserted version table
Asserted Versioning
Asserted Versioning database
Asserted Versioning Framework (AVF)
assertion begin date
assertion end date
assertion time
assertion time period
business key
reliable business key
unreliable business key
