Databases Reference
In-Depth Information
12/31/9999, this being exactly the same effective time period
previously (in assertion time) represented by row 1 alone.
This description of Asserted Versioning's basic diagram has
focused on a sample table whose contents reflect one temporal
insert transaction, and one temporal update transaction.
Additional Diagrams and Notations
Before proceeding, we need a more flexible way to supple-
ment English in our discussions of Asserted Versioning. In the
last section, we used what we called the “basic diagram” of an
asserted version table. That diagram contains five main compo-
nents. They are:
(i) The current clock tick, which indicates what time it is in the
example;
(ii) A temporal insert, update or delete transaction;
(iii) A calendar timeline covering approximately four years, in
monthly increments;
(iv) A stacked series of assertion time snapshots of the table
used in the example; and
(v) The table itself, including all rows across all effective and
assertion times.
We will still need to use this basic diagram to illustrate many
points. But for the most part, discussions in the next several
chapters will focus on effective time. So we will often use a dia-
gram in which rows in past assertion time are not shown in the
sample table, and in which there are no assertion time snapshots
either.
So, leaving assertion time snapshots out of the picture, we
will often use the kind of diagram shown in
Figure 6.3
. And
sometimes we will simply show a few rows from a sample table,
as in
Figure 6.4
.
Sep10
UPDATE Policy [P861, , PPO] Jun 2010
Jan
2010
Row
#
1
2
3
Jan
2011
Jan
2012
Jan
2013
Jan
2014
eff-end
epis-
beg
oid
eff-beg
asr-beg asr-end
client
type
copay
row-crt
P861
Jan10
Apr10
Apr10
Jan10
Jan10
Jan10
Jan10
C882
C882
C882
HMO
HMO
PPO
$15
$20
$20
Jan10
Apr10
9999
9999
9999
P861
Jul10
Oct10
Apr10
P861
Jul10
Jul10
Jul10
Figure 6.3 The Effective Time Diagram.
