The described information is valid since January 1, 2005; thus, the valid time interval
of the objects in the data warehouse is [01/01/05,now].
On March 1, 2005, the price of the product having code ???X2??? changes from ???$20???
to ???$25.??? In Figure 3 this update is reported. In particular, the time interval of the
simple node Price changes from [01/01/05,now] to [01/01/05, 28/02/05], and the
same for the time interval of the edge ProdPrice between the complex node Prod-
Temporal Semistructured Data Models and Data Warehouses 28
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uct and the simple node Price. The interval [01/01/05, 28/02/05] means that the
considered objects were valid from January 1, 2005 to February 28, 2005.
The new price is represented by means of the new simple node Price with value
???$25??? and valid time interval [01/03/05,now], related to the complex node Product,
representing the product having code ???X2,??? by means of the edge ProdPrice with
valid time interval [01/03/05,now]. The dashed region in Figure 3 contains the old
and the new prices.
$10
X1
$20
X2
Figure 2.
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