Front cover Best Practices for SAP BI using DB2 9 for z/OS Benefits of SAP Business Information Warehouse on z/OS Best practices and troubleshooting Scalability of the BI Accelerator Lydia Parziale Wilfried Alle Martin Cardoso Lindy Crawford Giovanni Grita Theodor Kuebler Georg Mayer ibm.com/redbooks International Technical Support Organization Best Practices for SAP BI using DB2 9 for z/OS March 2008 SG24-6489-02 Note: Before using this information and the product it supports, read the information in “Notices” on page ix. Third Edition (March 2008) This edition applies to DB2 Version 9 for z/OS, Release 1, and SAP BI Version 7.0 . © Copyright International Business Machines Corporation 2005, 2007, 2008. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . ix Trademarks . x Preface . xi The team that wrote this IBM Redbook . xii Become a published author . xv Comments welcome. xv Chapter 1. Introduction. 1 1.1 Product overview. 2 1.2 The audience for this IBM Redbooks publication . 3 1.3 Why run SAP BI on IBM System z . 4 1.3.1 Value provided by System z, z/OS, and DB2 . 4 Chapter 2. Overview of SAP BI and related data . 9 2.1 BI architecture . 10 2.2 Which cubes, DSO, and PSA objects are in your BI system. 12 2.2.1 Report SAP_BWTOOLPGM_DB2 . 13 2.3 BI data and DB2 partitioning . 14 2.3.1 Why partitioning . 15 2.3.2 Range partitioning of F- fact tables . 17 2.3.3 Partitioning of PSA tables . 19 2.3.4 Partitioning of DataStore objects. 20 2.3.5 Usage of data partitioned secondary indexes (DPSI) . 21 2.4 SAP BI snowflake schema . 25 2.5 New features and functions of SAP BI 7.x . 26 2.6 Terminology: BI objects and processes . 27 Chapter 3. Top ten SAP BI recommendations . 29 3.1 Base recommendations - SAP BI implementations for DB2 on z/OS . 30 Chapter 4. Benefits of DB2 9 for SAP BI . 35 4.1 Dynamic index ANDing for star schema queries. 36 4.2 Database statistics for BI tables . 39 4.2.1 Processing RUNSTATS for BI tables . 40 4.2.2 New to DB2 9: histogram statistics . 45 4.3 Parallelism enhancements . 48 4.3.1 Global query optimization . 48 4.3.2 Cross query block optimization . 49 © Copyright IBM Corp. 2005, 2007, 2008. All rights reserved. iii 4.4 Extended sparse index and in-memory workfile . 49 4.5 TRUNCATE TABLE statement . 50 4.6 FETCH FIRST n ROWS ONLY in subselects . 51 4.7 RENAME INDEX . 53 4.8 RANK expression . 53 4.9 Further DB2 9 enhancements and new features. 53 Chapter 5. Best practices for PSA . 55 5.1 Load PSA . 56 5.1.1 Load PSA . 58 5.1.2 Management of PSA . 68 5.1.3 Load PSA DB2 compression. 69 5.1.4 PSA partitioning . 70 Chapter 6. Best practices for InfoCubes. 73 6.1 Types of InfoCubes . 76 6.1.1 Physical data stores (data targets) . 76 6.1.2 VirtualProviders. 76 6.2 Repartitioning of InfoCubes. 78 6.2.1 Repartitioning implementation. 80 6.2.2 Advantages of partitioning/repartitioning. 88 6.3 Remodeling InfoProviders . 89 6.3.1 Procedure for remodeling an InfoProvider . 91 6.3.2 Benefits of remodeling InfoProviders . 96 6.4 SAP compression for loads . 96 6.4.1 Advantages . 96 6.4.2 Data validation . 97 6.4.3 Cumulative data versus non-cumulative key figures. 98 6.4.4 Areas of impact . 98 6.4.5 Implementing SAP compression . 100 6.4.6 Speed up compression of non-cumulative cubes . 100 6.4.7 Best practices for compressing large requests . 100 Chapter 7. Best practices for DataStore . 103 7.1 Differences between DataStore and ODS. 104 7.2 Types of DataStore . 104 7.2.1 Standard DataStore object . 104 7.2.2 DataStore object for direct update . 105 7.2.3 Write-optimized DataStore object . 105 7.3 Secondary indexes on DataStore objects . 105 7.3.1 Creating a secondary index on a DataStore object (DSO) . 107 7.4 Partitioning and clustering . 108 7.4.1 Choosing the partitioning key . 110 7.4.2 Choosing and changing the clustering index . 112 iv Best Practices for SAP BI using DB2 9 for z/OS 7.4.3 Data Partitioned Secondary Indexes (DPSIs) . 112 7.4.4 Partitioning a DataStore object . 114 7.5 DB2 compression . 132 7.5.1 Materialized query tables . 133 Chapter 8. Query and Load performance . 135 8.1 Troubleshooting general system performance . 136 8.2 Analyzing load performance . 142 8.3 Analyzing query performance . 157 8.3.1 Starting the analysis from ST03 . 158 8.3.2 Determining whether aggregates are required . 161 8.3.3 Front-end processing time . 164 8.3.4 Database performance . 165 8.4 DB2 Visual Explain . 174 8.5 SAP Query Analysis Tool . 178 8.5.1 Display of SQL access plan . 180 8.5.2 SAP Query Visualizer . 186 8.5.3 Features of SAP Query Visualizer . 190 8.5.4 Example of using the query analysis tool . 192 Chapter 9. SAP BI Accelerator . 195 9.1 The BIA architecture . ..