In addition to a summary
table for the NWAY aggregation, summary tables can also be provided
for other aggregations. Aggregation tables contain presummarized data
for any combination of dimension levels. This feature enables cubes
to access summarized numbers quickly. Aggregated data can be created
and automatically stored in MOLAP (Multidimensional OLAP) tables as
the cube is built or manually stored in ROLAP (Relational OLAP) tables
and linked into the cube.
All aggregation tables
must contain a column for each measure in the cube where the statistic
for the measure is one of the following: N, NMISS, SUM, MAX, MIN,
or USS. An aggregation table can be used in two ways:
-
as an NWAY data source for the
cube. In this case, the table must contain a column for every level
in the cube and a column for every stored measure.
-
as a subaggregation for the cube.
In this case, the table must include a column for each level of the
aggregation and a column for every stored measure.
When planning your aggregation
tables, note that the column names and attributes (type, format) must
be consistent across all input tables for a cube. Aggregation tables
require the following structure and organization.
-
one column for each dimension level
in the aggregation
-