Databases Reference
In-Depth Information
Posted Projections: Past Claims About the Future
The Posted Projections dataset consists of all those rows in
an asserted version table which lie in the assertion time past
but in the effective time future. Its subject matter is things
as they might have turned out to be. Its rows are claims about
these things which we are no longer willing to make. Posted
Projections are a record of all the times we got it wrong about
what currently lies in the future, up to but not including our
current claims about that future. Those current claims, of course,
are the ones in which we finally, we hope, got it right.
Here is the view which re-presents Posted Projections. With the
suffix “Post_Proj” standing for “posted projections”, it looks like this:
CREATE VIEW V_Policy_Post_Proj
AS SELECT oid, asr_beg_dt, asr_end_dt, eff_beg_dt, eff_end_dt,
client, type, copay
FROM Policy_AV
WHERE asr_end_dt
Now()
<¼
AND eff_beg_dt
Now()
>
The Posted Projections dataset is also a bi-temporal collec-
tion of data, and so both time periods must be included on all
rows in the view. The unique identifier for this or for any other
bi-temporal view of an asserted version table, is the combination
of oid, any one or both of the assertion dates, and any one or
both of the effective dates.
The rows in this view are mistakes which never became effec-
tive. In a more sinister light, they are forecasts which never came
true, and which those making them perhaps knew or suspected
would never come true. Note, however, that we can certainly
be held responsible for statements about what never came to
be. We can be held responsible for a statement made by any
row that has ever existed in current assertion time. In this case,
these rows were once asserted. Once upon a time, they were
claims made about what the future will be like. Bernie Madoff
is in jail for making such claims.
what we used to claim
what we currently claim
what we will claim
what things
used to be like
what things
are like
what things
will be like
what we used to claim
things will be like
Figure 13.6 Posted Projections.
