Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

4.7 RENAME INDEX
DB2 8 for z/OS only supports RENAME TABLE. RENAME INDEX was a feature
request from SAP BI, because the renaming of tables and their corresponding
indexes is used within SAP BI by functions like ACR (aggregate change run).
DB2 9 now supports RENAME INDEX and therefore speeds up the ACR.
4.8 RANK expression
Online analytical processing (OLAP) specifications provide the ability to return
ranking and row numbering information as a scalar value in the result of a query.
DB2 9 supports the new expressions ROW CHANGE, RANK, DENSE_RANK,
and ROW_NUMBER, which are sometimes referred to as OLAP-specification or
window functions.
RANK() returns the rank of each row within the partition of a result set. The rank
of a row is one plus the number of ranks that come before the row in question.
SAP BI uses the RANK expression for TOP-N queries.
Example 4-4 displays the ranking of employees that have a total salary of more
than $50,000, in order by name.
Example 4-4 Example for RANK
SELECT EMPNO, NAME, SALARY+BONUS AS TOTAL_SALARY,
RANK() OVER(ORDER BY SALARY+BONUS DESC) AS RANK_SALARY
FROM EMPLOYEES
WHERE SALARY+BONUS > 50000
ORDER BY NAME;
SAP BI uses the RANK expression for TOP-N queries.
4.9 Further DB2 9 enhancements and new features
There are additional important DB2 9 enhancements and new features having no
extra SAP BI specific usage but that are a general benefit for every SAP system.
Some of these additional enhancements include backup and recovery, Online
REORG, Universal tablespaces, Clone table support, MERGE statement, Index
Compression, OSC, LOB improvements, and XML.
Chapter 4. Benefits of DB2 9 for SAP BI 53