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

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3.1 Base recommendations - SAP BI implementations for DB2 on z/OS There is a base set of recommendations for SAP BI implementations on DB2 9 on z/OS. When followed, customers have demonstrated greater maintenance and query stability, resulting in better performance of the SAP BI on System z installation. These recommendations are: 1. Review your data model with respect to query performance. We strongly recommend being careful in your BI modeling. If your modeling has any weakness, this can lead to performance trouble later on and there is no guarantee that these performance issues can be solved by tuning the DB2 database. A good way is to follow the recommendations from the SAP BI performance workshop. Some examples of a weak design are: – Dimensions with too many characteristics that are queried, say, more than 16. – Unbalanced hierarchies. – Multi-provider over a large number of cubes, where many queries are accessed for many cubes. See SAP note 629541 for details. 2. Utilize SAP options to improve performance. Before tuning the DB2 database, first apply and check the following SAP BI query tuning methods: – Define aggregates as needed and use overnight or spare system capability to fill them. – Use the OLAP cache. – Use the pre-calculation of Web templates. – Evaluate the usage of BIA. 3. Set DB2 ZPARMS as per SAP note 390016. The ZPARM settings provided in SAP note 390016 have been recommended by IBM as optimal for SAP BI. Customers should check this SAP note for updates as part of their regular DB2 and SAP maintenance schedules. After migration to DB2 9, adapt the ZPARMS as described in SAP note 1032273. The most important change for BI is the new parameter MXDTCACH, which replaces the former ZPARM SJMXPOOL. 4. Ensure that the user selects the option to run RUNSTATS after data loads. 30 Best Practices for SAP BI using DB2 9 for z/OS
A cost-based optimizer relies on current and correct statistics to ensure optimal SQL access path selection. In an SAP BI environment, statistics do not require re-collection unless the object's data content has altered based upon a load, SAP compression, rollup, deletion, attribute change run, or data archive. Therefore it is only these activities that require the updating of DB2 statistics, and mostly the RUNSTATS are triggered automatically by the SAP BI functions itself. With a load, new packets are loaded into the F- fact table. Without knowledge of the newly loaded data, the optimizer may not choose an optimal access path for subsequent reporting queries, aggregate rollups, or SAP compressions that specify a search criteria for the individual packet number. Therefore it is important to ensure the RUNSTATS is triggered as part of the load process by selecting RSA1 → Manage InfoCube → Performance → Create Statistics (Btch). For process chains see SAP Note 778437. 5. Keep current with SAP support packs and DB2 maintenance level. Each new SAP support pack delivers fixes and also performance enhancements based upon prior customer requirements or identified areas for improvement by joint DB2 and SAP development. As with the SAP software, each maintenance release of DB2 provides additional fixes and enhancements based upon prior customer problems and requirements. To minimize exposure to known problems, we recommend that you stay current with the SAP certified maintenance level and apply additional PTFs identified in SAP note 81737. 6. Utilize SAP compression (E- fact table). When F- fact table packets are consolidated into the E- fact table via a process known as InfoCube compression, queries on the E- fact table filter by meaningful dimension/master data characteristics rather than the arbitrary packet number. This can result in better exploitation of available indexes on the E- fact table since the F- fact table must carry an index led by packet number to improve compression and rollup performance, but not query performance. Given the volatility of the F- fact table, RUNSTATS is required more frequently than on the E- fact table. Therefore keeping the F- fact table a moderate size by compressing packets to E can improve overall RUNSTATS performance and cost for the entire InfoCube. And finally the most important reason for SAP compression is for non-cumulative key figures whereby an additional row is inserted or updated in the E- fact table holding for each combination of dimension IDs the most current key figure values. Rather than requiring to sum all delta values from Chapter 3. Top ten SAP BI recommendations 31
Page 1: Best Practices for SAP BI using DB2
Page 4 and 5: Note: Before using this information
Page 6 and 7: 4.4 Extended sparse index and in-me
Page 8 and 9: 11.3 SAP BI database and InfoCube l
Page 10 and 11: viii Best Practices for SAP BI usin
Page 12 and 13: Trademarks The following terms are
Page 14 and 15: The team that wrote this IBM Redboo
Page 16 and 17: Thanks to these authors from the Pr
Page 18 and 19: ► Send your comments in an e-mail
Page 20 and 21: 1.1 Product overview The business w
Page 22 and 23: In general, database administrators
Page 24 and 25: ► Horizontal growth is achieved b
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Page 28 and 29: 2.1 BI architecture Figure 2-1 show
Page 30 and 31: New term Old term Analysis authoriz
Page 32 and 33: negative values means missing stati
Page 34 and 35: - When calculating database statist
Page 36 and 37: If you specify a partitioning schem
Page 38 and 39: Important: Never partition a PSA ta
Page 40 and 41: Figure 2-10 DPSIs versus NPSIs Figu
Page 42 and 43: Finally, Figure 2-12 explains which
Page 44 and 45: Figure 2-14 shows how the snowflake
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Page 54 and 55: 4.1 Dynamic index ANDing for star s
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Page 58 and 59: 4.2.1 Processing RUNSTATS for BI ta
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Page 64 and 65: Often the single-value based freque
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Page 70 and 71: condition, generated by SAP BI upon
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Page 74 and 75: 5.1 Load PSA In this section we dis
Page 76 and 77: 5.1.1 Load PSA To load data into th
Page 78 and 79: After the source system, the DataSo
Page 80 and 81: Note the available tabs (registers)
Page 82 and 83: Figure 5-8 shows the provided optio
Page 84 and 85: Figure 5-10 shows the following:
Page 86 and 87: The PSA table name is created autom
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Page 92 and 93: An InfoCube, whether data target or
Page 94 and 95: 6.1 Types of InfoCubes Data targets
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6.2.1 Repartitioning implementation
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You will then be presented with a w
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From within the monitor you are abl
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Once your repartitioning process is
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Figure 6-14 is displayed once you h
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When you remodel an InfoProvider yo
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Figure 6-17 demonstrates how you wo
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At this step of the process you are
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6.3.2 Benefits of remodeling InfoPr
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6.4.3 Cumulative data versus non-cu
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Important: After the initial compre
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► Use DPSIs for the cube’s E- f
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7.1 Differences between DataStore a
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Figure 7-1 shows the initial status
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4. By selecting the Create button,
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Partitioning and clustering are bot
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7.4.2 Choosing and changing the clu
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7.4.4 Partitioning a DataStore obje
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From the ABAP Dictionary: Utility f
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Figure 7-9 DB2/390 Storage Attribut
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partitioning was used. The CREATE T
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, "/BIC/RECORDMODE" POSITION( 00289
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Upon completion of the job, you wil
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| "/BIC/DIVISION" VARGRAPHIC (00000
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| sql: | DELETE FROM DDSTORAGE | WH
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| "/BIC/CRMEM_VAL" DECIMAL (000017,
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| DDL time(___8): .........4 millis
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134 Best Practices for SAP BI using
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8.1 Troubleshooting general system
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You need to ascertain: ► Which us
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Further information about the subje
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8.2 Analyzing load performance In t
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We use transaction ST03 → Expert
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Click the Details tab of the RSMO w
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Select the component of interest to
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Figure 8-11 All statistical records
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Figure 8-13 Single statistical reco
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Loading from a flat file You can av
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and right-click to select the Simul
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Note: You must activate the saving
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5. In the right-hand panel of the w
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If your query has long run times th
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that the query runs against → Mai
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If the main component of query perf
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► Display Statistics Data (to sho
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Select the appropriate button, ente
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Figure 8-29 Statement details To ch
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The ratio (ST04 statement cache “
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Figure 8-32 Visual Explain - SQL te
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8.5 SAP Query Analysis Tool The SAP
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Display of sql access path SQL quer
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The access path is displayed hierar
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The table information tab shown in
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DB2 Plan Table Figure 8-42 DB2 plan
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Graphical view of each query block
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Now you see the graphical view of t
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8.5.4 Example of using the query an
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9.1 The BIA architecture Figure 9-1
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Figure 9-2 BIA t-shirt sizing The B
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From the hardware side, the BIA is
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9.7 Overview The improvement of the
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10.1 SQL efficiency for DSO Queries
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The first join predicate is "/BIC/A
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Figure 10-5 Associate local predica
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Step 3 is repeated for each master
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Using the InfoCube query example in
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The first join predicate in Figure
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Thus, we have broken down the origi
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Figure 10-14 Comparing filtering Th
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AND "/BIC/AZOSASALE00"."PLANT" = "/
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Column Local or join CALMONTH Local
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10.4 Indexing of InfoCubes The defa
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11.1 Background To be more competit
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11.2.1 Hardware and software config
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11.2.2 Network infrastructure IBM S
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the chassis for blade-to-blade conn
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As part of the pre-benchmark planni
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11.4 Test case scenarios The goal o
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Figure 11-3 explains the data flow
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In addition, each cube, especially
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Measurement results Table 11-2 prov
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Figure 11-7 shows the average CPU u
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The number of queries per hour show
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Figure 11-10 shows that the average
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11.5.1 Recommendations for configur
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12.1 Terminology: BI objects and pr
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Metadata plays a fundamental role i
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12.3 Dataflow in SAP BI Data flow i
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12.4 Information access As previous
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Predecessor Successor WW Sales Euro
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An InfoCube in SAP BI can have up t
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12.8 Aggregates 4. The dimension ta
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The next example is an aggregate th
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For example, assume that different
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can be updated into InfoCubes or ot
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Figure 12-11 shows the steps that o
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Figure 12-12 on page 279 shows the
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The content, depicted in Figure 12-
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considerably more data records are
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The nodes stand for data sources, t
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values, hierarchies, hierarchy node
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BI SAP Query Connector A resource a
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Business Intelligence Cockpit Web-b
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processors in terms of macros that
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Crystal Reports Designer Design com
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Similar to the OLAP-standard term c
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P table Master data table for time-
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The process instance contains the m
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Relational Query Model An abstracti
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SAP Business Information Warehouse
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source object element Component of
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elements to be displayed in the Web
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Web application object catalog Web
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You insert one or more queries in t
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IT scenario The environment we used
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Checks under z/OS and DB2 We recomm
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To check that the SAPCL procedure w
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List of SAP BW OSS Notes Table C-1
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SAP BI on DB2 for z/OS 390016 BW Da
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Network configuration: static multi
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START CU091060 START CU0A1070 START
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Table name Average row length Total
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Table name Average row length Total
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Parameters BPK16K0 BPK16K1 VIRTUAL
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drwxr-xr-x 3 t11adm sapsys 2048 200
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Example D-6 shows a cube index crea
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B49/S_RTNSVAL 24 DECIMAL 17 2 N 4 N
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-rw-r--r-- 1 t11adm sapsys 2084482
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-rw-r--r-- 1 t11adm sapsys 547449 2
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Online resources These Web sites ar
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Help from SAP SAP Support and downl
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C Candidates for partiioning Data W
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M master data 155, 211, 258, 277 si
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star schema 265-266 also see InfoCu
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Best Practices for SAP BI using DB2
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Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

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