|Oracle9i OLAP User's Guide
Release 2 (9.2)
Part Number A95295-01
Developing a Summary Management Strategy, 6 of 7
When creating MVs for the OLAP API, you should create materialized views for each cube that represent a star schema. The cube must be mapped to a single fact table, and the fact table may contain only lowest-level data.
CWM metadata, you can choose to create fact materialized views using concatenated rollup syntax or grouping set syntax. For
CWM2 metadata, only grouping set style fact MVs are supported.
When you use OLAP Summary Advisor, fact materialized views are created automatically for each hierarchy combination of a
CWM cube. The materialized views are created with concatenated rollup syntax.
Alternatively, you can use the
CREATEFACTMV_GS procedures in the
DBMS_ODM package to create a fact materialized view for a
CWM2 cube. The materialized view is created with grouping set syntax.
The number of fact materialized views for a cube depends on whether you using concatenated rollup style MVs or grouping set MVs.
If you use OLAP Summary Advisor, you will generate a separate concatenated rollup style MV for each combination of hierarchies in the cube. If you use
DBMS_ODM, you will generate a single grouping set style MV for the cube.
For example, the
SALES_CUBE cube in the Sales History (
SH) schema, described in Table 28-1, would have either one materialized view generated with grouping sets or four materialized views generated with concatenated rollup.
SALES_CUBE, there would be a separate concatenated rollup materialized view for the each of the following dimension hierarchy combinations.