Databases Reference
In-Depth Information
May10
UPDATE Policy [P861, , , $20]
Jan10
The table as asserted from Jan 1
st
, 2010 to May 1
st
, 2010
1
The table as asserted from May 1
st
, 2010 until further notice
May10
2
1
3
Jan
2010
Jan
2011
Jan
2012
Jan
2013
Jan
2014
Temporal Primary Key
Temporal Foreign Key
Episode Begin Date
Row
#
1
2
3
oid
eff-beg
asr-beg
asr-end
epis-
beg
type
eff-end
client
copay
row-crt
P861
Jan10
9999
Jan10
May10
Mar10
C882
C882
C882
HMO
$15
$15
$20
Jan10
Jan10
May10
May10
May10
May10
Jan10
Jan10
HMO
May10
May10
P861
9999
9999
1
9999
HMO
Row Creation Date
Effective Period
Assertion Period
Figure 6.2 The Basic Asserted Versioning Diagram.
On January 2010, a temporal insert transaction was processed
for policy P861.
1
It said that policy P861 was to become effective
on that date, and that, as is almost always the case when a tem-
poral transaction is processed, was to be immediately asserted.
Then in May, a temporal update transaction for that policy
was processed. The transaction changed the copay amount from
$15 to $20, effective immediately. But this invalidated row 1
because row 1 asserted that a copay of $15 would continue to
be in effect after May. So as part of carrying out the directives
specified by that temporal transaction, we
withdrew
the asser-
tion made by row 1, by overwriting the original assertion end
date of 12/31/9999 on row 1 with the date May 2010.
When a row is withdrawn, it is given a non-12/31/9999 asser-
tion end date. Withdrawn rows, in these diagrams, are graphically
1
The format for showing bi-temporal dates, in the text itself, is slightly different from
the format used in the sample tables. For example, a date shown as “Jan10” in any of
the tables will be written as “January 2010” in the text. Time periods are shown in the
text as date pairs with the month still shortened but the century added to the year.
Thus “[Feb 2010 - Oct 2012]” designates the time period beginning on February 2010
and ending one clock tick before October 2012, but would be represented in the
diagram by “Feb10” and “Oct12”.
