Databases Reference
In-Depth Information
The second column holds the Object_Key. The Object_Key uniquely
identifies each individual object. If a single object (e.g., small french fries,
chair, or 16 oz. can of beans) occurs in a single transaction three times, those
three occurrences within a single transaction will be summarized to one row
of data, marked by the Itemset_Key that uniquely identifies the transaction
and the Object_Key that uniquely identifies the object. For every Itemset
wherein that object occurs, in each Itemset that object will be identified by
the same Object_Key value. So, the object
small french fries
is identified by
the same Object_Key every time it occurs. Likewise, every object is identi-
fied by the same Object_Key every time it occurs.
The remaining columns hold the metric measurements of the transac-
tion that is the Itemset. In Table 5.1, the metric measurement columns are
Quantity and Dollars. These columns should be defined to fit the transac-
tion of your enterprise. Your enterprise transaction may include a differ-
ent set of transaction metrics. If so, then rather than Quantity and Dollars
the Market Basket Table should include columns that reflect the transac-
tion metric measurements of your enterprise transaction.
Chapter 6 will discuss the physical structure of the Market Basket
Table. Chapter 7 w ill discuss the ETL application that will populate
the Market Basket Table, including the curious-looking first row for
tABle 5.1
Market Basket Table
Itemset_key
Object_key
Quantity
Dollars
1
0
0
$0.00
1
15
1
$15.31
2
16
2
$24.42
2
43
1
$14.32
2
57
2
$18.18
2
64
1
$12.37
3
15
2
$30.62
3
16
1
$12.21
3
64
1
$12.37
3
78
4
$53.76
3
98
1
$2.45
4
43
3
$42.96
4
57
1
$9.09
4
78
1
$13.44
4
87
1
$16.87
4
98
1
$2.45
