A simple, but extremely useful, strategy for using a
materialized view is to use selection on the materialized view,
or rollup on the materialized view by grouping and
aggregating on additional columns. For example, assume that
a materialized view contains the total sales by quarter for
each product. This materialized view can be used to answer a
query that requests the total sales of Levi’s jeans for the year
by first applying the selection and then rolling up from
quarters to years. It should be emphasized that the ability to
do roll-up from a partially aggregated result, relies on
algebraic properties of the aggregating functions (e.g., Sum
can be rolled up, but some other statistical function may not
be).
A simple, but extremely useful, strategy for using amaterialized view is to use selection on the materialized view,or rollup on the materialized view by grouping andaggregating on additional columns. For example, assume thata materialized view contains the total sales by quarter foreach product. This materialized view can be used to answer aquery that requests the total sales of Levi’s jeans for the yearby first applying the selection and then rolling up fromquarters to years. It should be emphasized that the ability todo roll-up from a partially aggregated result, relies onalgebraic properties of the aggregating functions (e.g., Sumcan be rolled up, but some other statistical function may notbe).
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