Databases Reference
In-Depth Information
We begin with the delete cascade transaction itself. Let's
assume that it is taking place on November 2013. The transac-
tion looks like this:
DELETE FROM Client [C903,, ] Oct2010, Mar2011
The temporal foreign key metadata table (Figure 8.4) directs
the AVF to apply the delete cascade option to this temporal
transaction. After the transaction successfully completes, the
database will no longer assert that client C903 is in effect in
the time period [Oct 2010 - Mar 2011]. Also, the database will
no longer assert that there are any policies owned by this client
that are in effect during those same five months.
Figure 11.2
shows the current state of the Client and Policy
tables, as represented in
Figure 11.1
. However, we have removed
the history of how the tables reached those states. In other
words, in
Figure 11.2
we do not show the withdrawn assertions
that were part of the history leading up to that state of the data-
base. Instead, we show only the currently asserted versions of
our two clients and one policy.
The first step is to apply the delete transaction to its target,
client C903. Within the target timespan of [Oct 2010 - Mar 2011],
Client Table
Row
#
1
2
3
4
5
6
7
8
9
10
oid
eff-beg
eff-end
asr-beg
asr-end
epis-
beg
client-
nbr
X457
X457
X457
D834
D834
D834
Z119
Z119
Z119
Z119
client-nm
row-crt
C903
Apr10
Jun10
Sep10
Jan11
Apr12
Feb13
Jan10
Nov10
Nov12
Aug13
Jun10
Sep10
Jan11
May11
Sep12
Apr10
9999
9999
9999
9999
9999
9999
9999
9999
9999
9999
Apr10
Jones
Roberts
Colbert
Powers
Smith
Williams
Cooper
Matthews
Smith
Nelson
Apr10
Jun10
Sep10
Jan11
Apr12
Feb13
Jan10
Nov10
Nov12
Aug12
C903
C903
C903
C903
C903
C882
C882
C882
C882
Jun10
Sep10
Jan11
Apr12
Feb13
Jan10
Nov10
Nov12
Aug13
Apr10
Apr10
Apr10
Apr12
Feb13
Jan10
Jan10
Nov12
Aug13
9999
Nov10
Mar11
Jan13
9999
Policy Table
Row
#
1
oid
eff-beg
eff-end
asr-beg
asr-end
epis-
beg
Feb10
client
type
copay
row-crt
Jul10
May11
Mar12
Apr12
Aug12
Jan13
Oct13
9999
Feb10
Jul10
Nov11
Nov11
Apr12
Aug12
Mag13
Oct13
9999
C882
PPO
$20
$20
$30
$40
$50
$40
$40
$40
Feb10
Jul10
Nov11
Mar12
P861
P861
P861
P861
P861
P861
P861
P861
Feb10
Jul10
Nov11
Mar12
Apr12
Aug12
May13
Oct13
2
3
4
5
6
7
8
9999
9999
9999
9999
9999
9999
9999
Feb10
Nov11
Nov11
Nov11
Nov11
May13
May13
C903
PPO
HMO
POS
POS
C882
C882
C882
C882
Apr12
Aug12
PPO
PPO
PPO
C903
May13
Oct13
C882
Figure 11.2 A Temporal Delete Cascade: Before the Transaction.
