*.*
(assuming that the order-code of 1999 is 0). Note that only the first matching indextuple
(corresponding to the Day level) suffices for generating the corresponding
h-surrogate specification, since all days of 1999 have the same h-surrogate prefix:
0.. This single index-tuple retrieval is an extremely fast implementation of the Create_
Range abstract operation of Figure 5(a).
The same holds for the PRODUCT dimension also, since another HPP restriction
is imposed there. The corresponding h-surrogate specification for the restriction
Category = ???Air Condition??™ is 3.*.* (assuming that the order-code of the ???Air Condition??™
value is 3). For dimension LOCATION things are a bit different since we
have to perform a full table scan directly on the base table and then select the tuples
that match the restriction on the feature attribute Population, which is functionally
dependent on the hierarchical attribute Area. The corresponding h-surrogate speci-
fication is 2.6.* assuming that only one area (with order-code 6) in a single region
(with order-code 2) satisfies the restriction on the Population feature attribute.
As soon as the h-surrogate specifications are extracted from each dimension, they
are combined into a single chunk expression (CX) that is passed as input to an
MDRangeSelect operator. A chunk expression is essentially an access pattern describing
the cells that must be accessed in each depth of the chunk-tree and exploits
the chunk-id notation.
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