Summary

This chapter discussed how to maintain characteristic and InfoCube data in BW.

Key Terms

Term	Description
Change run	The change run procedure activates characteristic data changes.
Request	A request is a data load request from BW Scheduler. Each time that the BW Scheduler loads data into an InfoCube, a unique request ID is created in the data packet dimension table of the InfoCube.
Aggregate rollup	The aggregate rollup procedure updates aggregates with new data loads.
InfoCube compression	InfoCube compression aggregates multiple data loads at the request level.
Reconstruct	The reconstruct procedure restores load requests from PSA.
Index	Indices are used to locate needed records in a database table quickly. BW uses two types of indices, B-tree indices for regular database tables and bitmap indices for fact tables and aggregate tables. See Chapter 13 for more information on bitmap indices.
Statistics	For a SQL statement, many execution plans are possible. The database optimizer generates the most efficient execution plan based on either the heuristic ranking of available execution plans or the cost calculation of available execution plans. The cost-based optimizer uses statistics to calculate the cost of available execution plans and select the most appropriate one for execution. BW uses the cost-base optimizer for Oracle databases.

For Further Information

• OSS Note 0181944, "Accelerate Hierarchy Attribute Change Run."

• OSS Note 0397403, "Aggregate Rollup Runs Slowly."

Next…

We will discuss how to tune query performance and load performance.