20 Tips and Tricks to Improve Data Load Performance Jesper Christensen COMERIT © 2012 Wellesley Information Services. All rights reserved.
In This Session … •
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Gain insight into SAP NetWeaver® BW data load processes, how they work, and what tools are available to monitor and optimize their performance Receive best practices to maximize data load performance while reducing long-term maintenance costs Understand the benefits of optimized data load processes Find out how to enable version history to track code changes and how to create reusable ETL logic to improve throughput and reduce data load time Get tips on when and how to use customer exits in DataSources and variables to manage risk and reduce maintenance costs Identify the challenges and benefits of semantic partitioning and the importance of efficient data models 1
What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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SAP NetWeaver BW Data Load Processing Overview •
SAP NetWeaver BW data load processing consists of three main activities: Extraction = Collecting the data in the source systems and preparing it before sending it to SAP NetWeaver BW Transformation = Transforming the data using routines, lookups, formulas, etc. Load = Updating the data into InfoProviders’ DataStore Objects (DSOs), cubes, and master data
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Dataflow in SAP NetWeaver BW
Source: SAP 4
Extraction Interface Types
Source: help.sap.com 5
DataSources Supported by SAP NetWeaver Extraction •
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SAP NetWeaver BW Service API Allows data from SAP systems in standardized form to be extracted and accessed directly These can be SAP application systems or SAP NetWeaver BW systems File interface The file interface permits the extraction from and direct access to files, such as csv files Web services Permit you to send data to the SAP NetWeaver BW system under external control
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DataSources Supported by SAP NetWeaver Extraction (cont.) •
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Universal Data (UD) Connect Permits the extraction from and direct access to relational data Database (DB) Connect Permits the extraction from and direct access to data located in tables or views of a database management system Staging Business Application Programming Interfaces (BAPIs) Open interfaces that SAP BusinessObjects DataServices and certified third-party tools can use to extract data from older systems
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Extraction Time Can Be Split into Two Categories •
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Extraction time DB time to select the data to be extracted Logic applied during extraction such as joins, lookups, and filtering Middleware and network time The time used to transfer the data from the source system to the target SAP NetWeaver BW system Interface types such as Web services and Universal Data (UD) Connect are good for small amounts of data and cannot handle large volumes Fixed format files are larger to transfer but faster to load into SAP NetWeaver BW WAN Network time can become a bottleneck during peak hours 8
Transformation Types •
SAP NetWeaver BW supports the 3.x and the 7.x versions of transforming the data 3.x is using Transfer rules and Update rules Two steps of logic to process the dataset Loads to different targets must be processed together Used to have better performance than transformations Old method; no more development or performance enhancements; do not continue to use 7.x is using transformations Is using a single step of logic to process the dataset Loads to different targets can be processed independently Better performance Always use this option for new development 9
Loading Data to Information Providers Types •
Loading of the data to InfoProviders differs depending on type DSO Update of the activation queue Activation of data (update of active table and changelog) SID determination Should in general be switched off for DSOs Master data Update of master data tables SID determination Check duplicate key values Very time consuming for time-dependent attributes Attribute change run to activate the master data Generate navigation data
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Loading Data to Information Providers Types (cont.) •
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Loading of the data to InfoProviders differs depending on type (cont.) Cubes Update of data to the InfoCube star schema SID determination Roll up data to aggregates Update data to SAP NetWeaver BW Accelerator (SAP NetWeaver BWA) Performance considerations for loading the data Ensure that the database parameters are in place Implement the correct SAP NetWeaver BW settings for your InfoProviders 11
What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Tip 01: SAP NetWeaver BW 7.x Statistics •
SAP NetWeaver BW includes a great statistics tool It collects information on most SAP NetWeaver BW-specific activity Such as data loads and queries It’s delivered as business content So you must activate it just like all business content How to Activate Admin Cockpit document on help.sap.com http://help.sap.com/saphelp_nw04s/helpdata/en/46/f9bd550d4 0537de10000000a1553f6/frameset.htm
Tip 01: SAP NetWeaver BW 7.x Statistics (cont.) •
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Define standard measure that can be monitored on a daily, weekly, and monthly basis to evaluate data load performance trends Records processed per minute or Time to process 1 million records Time spent on extraction Time spent in transformations Top 10 long running loads Total time spent for Attribute and Hierarchy change runs Use the standard queries and reports as a starting point 14
Tip 02: See Details About Performance in the Monitor •
The load monitor transaction code RSMO gives more details about the processing steps InfoPackage details Data Transfer Process (DTP) details
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Tip 03: Use SE30 to Test Performance •
Transaction code SE30 ABAP Runtime Analysis gives a detailed view of performance
Remember to set the accuracy to Low Run transaction code RSA3
Note: SE30 can also be used for transformations by simulating the DTP run 16
Tip 03: Use SE30 to Test Performance (cont.) •
Detailed Runtime will show you the bottlenecks
Sort descending based on Net Time and you will see your bottleneck on the top
What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Tip 04: Implement the Correct DB Parameters •
Key DB parameters SAP has recommended some parameter values for SAP NetWeaver BW that usually improve performance Expect to evaluate these parameter settings frequently, though, to ensure that the DB operates optimally See three key SAP Notes: 830576 – Parameter recommendations for Oracle 10g 387946 – Use of locally managed tablespaces for BW systems 1044441 – Basis parameterization for NW 7.0 BI systems
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Tip 05: Manage Database Statistics •
DB statistics are also crucial for SAP NetWeaver BW performance The DB will not know the most optimal execution path for an SQL statement without DB statistics To set up DB statistics: Set up BRCONNECT job using DB20 to recalculate DB statistics Use program RSANAORA to analyze specific tables DB statistics can run very slowly under Oracle when you use SAP NetWeaver BW programs or DB statistics. Make sure you use BRCONNECT.
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Tip 06: Build Secondary Indices •
The select statements used during extraction or during user exit enhancements should always use a database index Build secondary indices in transaction code SE11 or on the DSO objects used in select statements
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What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Tip 07: Coding Tips — Dynamic Calls •
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Code the extractor user exits so that they call a dynamic program per DataSource Isolate the code per DataSource in a self-contained program Minimize risk that a syntax error in code for one DataSource impacts extraction from all other DataSources Example Program name = ZBW + Form name = DOZBW + This same technique can be used with customer exit variable code
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Tip 07: Coding Tips — Dynamic Calls (cont.) •
Illustration: Sample dynamic program call
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Tip 08: Coding Tips — Field Symbols •
Performance consideration: Where possible, use field symbols to populate fields in the data package The move costs of a LOOP ... INTO statement depend on the size of a table line The larger the line size, the longer the move will take By applying a LOOP... ASSIGNING statement you can attach a field symbol to the table lines and operate directly on the line contents This is a much faster way to access the internal table lines without moving their contents
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Tip 08: User Exit — Field Symbols •
Illustration: Sample use of field symbols User Exit (without field-symbols)
User Exit (with field-symbols)
REPORT YBWZDS_AGR_USER. ***************************************************************** * Form called dynamically must start with DOYBW + *****************************************************************
REPORT YBWZDS_AGR_USER. ***************************************************************** * Form called dynamically must start with DOZBW + *****************************************************************
FORM DOYBWZDS_AGR_USER TABLES C_T_DATA STRUCTURE ZOXBWD0001.
FORM DOYBWZDS_AGR_USER TABLES C_T_DATA STRUCTURE ZOXBWD0001.
data: l_logsys type logsys. l_s_data like ZOXBWD0001.
data: l_logsys type logsys. field-symbols: like c_t_data.
select single logsys from t000 into l_logsys where mandt = sy-mandt. loop at c_t_data into l_s_data. l_s_data-load_dt = sy-datum. l_s_data-logsys = l_logsys. modify c_t_data from l_s_data index sy-tabix. endloop. ENDFORM.
select single logsys from t000 into l_logsys where mandt = sy-mandt. loop at c_t_data assigning . -load_dt = sy-datum. -logsys = l_logsys. endloop. ENDFORM.
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Tip 09: Coding Tips — Read Instead of Loop •
Use a READ statement to access a table rather than a LOOP WHERE The cost of a LOOP WHERE is much higher than a READ with table key or binary search statement The READ can also be used prior to a loop statement that does require a LOOP to then use a LOOP FROM INDEX instead of LOOP WHERE
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Tip 09: User Exit: Read Instead of Loop •
Illustration: Sample use of field symbols User Exit (without read)
User Exit (with read)
REPORT YBW2LIS_13_VDITM. ***************************************************************** * Form called dynamically must start with DOYBW + *****************************************************************
REPORT YBWZDS_AGR_USER. ***************************************************************** * Form called dynamically must start with DOZBW + *****************************************************************
FORM DOYBW2LIS_13_VDITM TABLES C_T_DATA STRUCTURE ZOXBWD0001.
FORM DOYBWZDS_AGR_USER TABLES C_T_DATA STRUCTURE ZOXBWD0001.
data: l_logsys type logsys. l_s_data like ZOXBWD0001.
data: l_logsys type logsys, l_idx type sy-tabix.
field-symbols: like c_t_data, like VBAP.
field-symbols: like c_t_data, like VBAP.
Loop at c_t_data assigning . Loop at itab assigning where VBELN = c_t_data-VEBLN. c_t_data-NETVALUE = c_t_data-NETVALUE + - NETWR. endloop. Endloop.
Loop at c_t_data assigning . READ TABLE ITAB WITH TABLE KEY VBELN = c_t_data-VEBLN BINARY SEARCH. L_idx = sy-tabix.
ENDFORM.
Loop at itab assigning FROM INDEX l_idx. check -VBELN = c_t_data-VEBLN. c_t_data-NETVALUE = c_t_data-NETVALUE + - NETWR. endloop. endloop.
ENDFORM.
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Tip 10: Delta Enable Generic DataSources •
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Improve extract performance by creating delta-enabled generic DataSources Simple: By date By timestamp By sequential number (unique table key) Complex: Pointers – ABAP techniques can be used to record an array of pointers to identify new and changed records
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Tip 10: Delta Enable Generic DataSources (cont.) •
Illustration: Delta enabling a generic DataSource
Ensure that you set the upper or lower limits correctly based on the data you are extracting!
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Tip 11: Lookups • •
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Do not use single selects for lookups! For better performance: Use start routines to read lookup data to an internal table Read internal table to populate field values in routines For best performance: Add lookup fields to InfoSource Use start routine and field symbols to populate blank fields for entire data package at one time (see illustration on slide titled ―User Exit — Field Symbols‖)
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Tip 12: Program Includes • • •
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Use includes for all complex routine logic Access logic by using ―perform‖ statements Increase portability of transformation logic Use same read statements for multiple lookups Reduce risk of errors in obscure places Decrease maintenance cost of complex update rules One place to go to fix/enhance logic Code is consistent and easier to follow Enable version management of code Track changes over time Compare between systems Revert to previous versions 32
Tip 12: Program Includes (cont.) •
Illustration – Select into internal table Start routine
Program include
FORM startup TABLES MONITOR STRUCTURE RSMONITOR "user defined monitoring MONITOR_RECNO STRUCTURE RSMONITORS DATA_PACKAGE STRUCTURE DATA_PACKAGE USING RECORD_ALL LIKE SY-TABIX SOURCE_SYSTEM LIKE RSUPDSIMULH-LOGSYS CHANGING ABORT LIKE SY-SUBRC. "set ABORT 0 to cancel update * *$*$ begin of routine - insert your code only below this line *-*
***************************************************************** * INITIALIZATION (ONE-TIME PER DATA PACKET) ********************* * TO READ FROM DATABASE (ALL RECORDS FOR DATA PACKAGE) ********** ***************************************************************** * FORM READ_USR02_TO_MEMORY_FOR_0BWTC_C02 *---------------------------------------------------------------* Form READ_USR02_TO_MEMORY_FOR_0BWTC_C02 TABLES MONITOR STRUCTURE RSMONITOR DATA_PACKAGE STRUCTURE /BIC/CS80BWTC_C02 USING RECORD_ALL LIKE SY-TABIX SOURCE_SYSTEM LIKE RSUPDSIMULH-LOGSYS CHANGING ABORT LIKE SY-SUBRC.
* fill the internal tables "MONITOR" and/or "MONITOR_RECNO", * to make monitor entries perform READ_USR02_TO_MEMORY_FOR_0BWTC_C02 TABLES MONITOR DATA_PACKAGE USING RECORD_ALL SOURCE_SYSTEM CHANGING ABORT. * if abort is not equal zero, the update process will be canceled * ABORT = 0. *$*$ end of routine - insert your code only before this line *-*
* Refresh the internal table. refresh: GT_USR02. * Read USR02 user data to memory for this data package select * into corresponding fields of table GT_USR02 from USR02 FOR ALL ENTRIES IN DATA_PACKAGE where BNAME = DATA_PACKAGE-TCTUSERNM order by primary key. * if abort is not equal zero, the update process will be canceled ABORT = 0. ENDFORM. "READ_USR02_TO_MEMORY_FOR_0BWTC_C02
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Tip 12: Program Includes (cont.) •
Illustration – Include perform statements Update routine
Program include
FORM compute_key_field TABLES MONITOR STRUCTURE RSMONITOR "user defined monitoring USING COMM_STRUCTURE LIKE /BIC/CS0BWTC_C02 RECORD_NO LIKE SY-TABIX RECORD_ALL LIKE SY-TABIX SOURCE_SYSTEM LIKE RSUPDSIMULH-LOGSYS CHANGING RESULT LIKE /BI0/V0BWTC_C02T-USERGROUP RETURNCODE LIKE SY-SUBRC ABORT LIKE SY-SUBRC. "set ABORT 0 to cancel update * *$*$ begin of routine - insert your code only below this line*-* * fill the internal table "MONITOR", to make monitor entries PERFORM READ_GT_USR02 USING COMM_STRUCTURE-TCTUSERNM RECORD_NO RECORD_ALL SOURCE_SYSTEM CHANGING GS_USR02 ABORT.
***************************************************************** * RECORD PROCESSING (RUN PER RECORD) **************************** * TO READ FROM MEMORY (ONE RECORD) ****************************** ***************************************************************** * FORM READ_GT_USR02 *---------------------------------------------------------------* FORM READ_GT_USR02 USING TCTUSERNM LIKE USR02-BNAME RECORD_NO LIKE SY-TABIX RECORD_ALL LIKE SY-TABIX SOURCE_SYSTEM LIKE RSUPDSIMULH-LOGSYS CHANGING GS_USR02 ABORT LIKE SY-SUBRC. "ABORT0 cancels update STATICS: L_RECORD LIKE SY-TABIX. IF RECORD_NO L_RECORD. L_RECORD = RECORD_NO. CLEAR GS_USR02. *
RESULT = GS_USR02-CLASS. *if abort is not equal zero, the update process will be canceled *$*$ end of routine - insert your code only before this line *-* ENDFORM.
Read user data from internal table GT_USR02 READ TABLE GT_USR02 WITH KEY BNAME = TCTUSERNM INTO GS_USR02.
ENDIF. ENDFORM.
"READ_GT_USR02
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Tip 13: Use Start and End Routines •
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Start routines can be used to process the data efficiently prior to starting the single records processing The most efficient place to delete records from the data package prior to spending time on processing them End routines in SAP NetWeaver 7.x allows for processing of the data after it has been passed through the transformation It is the most efficient place to copy data records (e.g., for generating year-to-date figures)
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What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Tip 14: Data Modeling: Defining Dimensions •
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Use as many dimensions as possible Separate common filter characteristics into own dimension Use line-item dimensions for high cardinality characteristics such as document numbers Do not set the high cardinality flag! Define related characteristics in the same dimension Calculate expected number of dimensional entries Try not to exceed 10% of expected fact table entries Verify the dimension design after the first dataloads using program SAP_INFOCUBE_DESIGNS Add all relevant time characteristics If 0CALMONTH is lowest granularity, add 0CALMONTH2, 0CALQUARTER, 0CALQUART1, 0HALFYEAR, and 0CALYEAR Provides greatest reporting flexibility without need to reload 37
Tip 15: Implement Semantic Partitioning •
What is it? An architectural design to enable parallel data loading and query execution Partitioning criteria: Year, Region, or Actual/Plan
Source: SAP
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Tip 15: Implement Semantic Partitioning (cont.) •
Benefits of semantic partitioning: Reduction in SAP NetWeaver BWA footprint (when partitioned by year) Parallel data loading (when not partitioned by year) Parallel query execution Best case when partitioning criterion is set as constant Almost as good to create variables to filter on 0INFOPROV Archival of a single InfoCube does not impact others Easier DB maintenance Performance benefits are so significant … semantic partitioning should be deployed on virtually every data model! 39
Tip 15: Implement Semantic Partitioning (cont.) •
Example: Semantic partitioning by year MultiProvider
History (Summarized)
ALL years Write-Optimized (No SIDs)
Ex: Current Current Current Current Current
Year Year Year Year Year
Current Year – 3
Current Year - 2
Current Year - 1
Current Year
Current Year + 1
Current Year – 3
Current Year - 2
Current Year - 1
Current Year
Current Year + 1
+ 1 = = - 1 = - 2 = - 3 =
2010 2009 2008 2007 2006
DataSource
Source: SAP
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What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Tip 16: Switch Off SID Determination for DSOs •
Switch off SID determination for DSOs that are not used in reporting SID determination is required only for report DSOs and take up 40-70% of the activation time
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Tip 17: Activate Parallel Processing •
Parallel processing is possible for most steps in SAP NetWeaver BW DTP Parallel Processing
DSO settings Transaction code RSODSO_SETTINGS
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Tip 18: Compress Data •
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Compression of InfoCubes helps with two things in the dataflow: Makes the tables that are updated smaller and hence faster to update The process variant that drops and recreates the indices during loading in a process deletes only the indices on the F-fact table and hence the time to rebuild indices is much faster Recommendation Compress data that is older than 2-8 days depending on your load schedule
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Tip 19: Implement Number Range Buffering of DIMs and SIDs •
The number range tables (NRIV) are called for every new distinct record that is loaded to SAP NetWeaver BW as either master data or dimension in an InfoCube The NRIV table is accessed with a select for update statement, which can be quite slow Buffering should be done as follows: Determine the large number ranges (Document numbers, Dimensions with documents or many distinct values) Goto t-code SNRO and set up buffering
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Tip 20: Implement SAP NetWeaver BW Accelerator •
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SAP NetWeaver BWA is superior to aggregates when it comes to improving performance Aggregates require continuous tuning as the data and query requirements change over time SAP NetWeaver BWA requires limited maintenance effort in comparison If you can afford it, you should invest in SAP NetWeaver BWA
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Tip 20: Implement SAP NetWeaver BW Accelerator (cont.) •
Disk speed is growing slower than other hardware components Technology Drivers 1990
2010
CPU
0.05
253.31
MIPS/$
MIPS/$
Memory
0.02
50.15
MB/$
MB/$
216
264
Addressable Memory
Network Speed
Disk Data Transfer
100
100
Mbps
Gbps
5
600
MBPS
MBPS
Architectural Drivers Improvement
5066x
2502x
248x 1000 x
120x
1990
2010
Disk-based data storage
In-memory data stores
Simple consumption of apps (fat client UI, EDI)
Multi-channel UI, high event volume, cross industry value chains
Generalpurpose, applicationagnostic database
Applicationaware and intelligent data management
Source: 1990 numbers SAP AG, 2010 numbers, Dr. Berg
Physical hard drive speeds grew by only 120 times since 1990.47All other hardware components grew faster.
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Tip 20: Implement SAP NetWeaver BW Accelerator (cont.) •
In this example, the average query execution took 58.8 seconds; after SAP NetWeaver BW Accelerator, the average query took 17.9 seconds (295% faster overall)
Source: SAP
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Tip 20: Implement SAP NetWeaver BW Accelerator (cont.) •
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With SAP NetWeaver BW 7.3, you can have data in SAP NetWeaver BW Accelerator; InfoCubes are not required This saves the loading time to the BW cube start schema You should implement SAP NetWeaver BWA if you want to consistently improve query performance and data load performance
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Tip 20: Implement SAP NetWeaver BW Accelerator (cont.) •
SAP NetWeaver BWA is an appliance, but it does require some maintenance activities to keep it running smoothly Monitor SAP NetWeaver BWA utilization to avoid overloading The rule of thumb is that you should have data that is less than 50% of the memory size Overloading SAP NetWeaver BWA will cause performance degradation Compress the cubes and rebuild indices on a regular basis SAP NetWeaver BWA is not a cheap toy. The licensing is based on blades used. Avoid using more space than needed by dropping and rebuilding the SAP NetWeaver BWA indices on a regular basis 50
Tip 20: Implement SAP NetWeaver BW Accelerator (cont.) •
Avoid aggregates but consider as a back up for SAP NetWeaver BW Accelerator They come at a cost Additional step in data loading Longer runtime for master data and hierarchy activations
Before aggregate creation: • Gather information about end-user query requirements and drill-down patterns • You can suggest aggregates based on query design • Execute the query multiple times using realistic drill-down scenarios
After aggregate creation: • Allow time for users to execute queries and collect SAP NetWeaver BW statistics • You can suggest aggregates based on SAP NetWeaver BW statistics • Analyze the use of aggregates • Modify aggregates for optimization
Check that the query is using the aggregate via RSRT 51
What We’ll Cover … • • • •
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Loading data in SAP NetWeaver BW Finding performance bottlenecks Optimizing the database Optimizing the ABAP code Optimizing the data models Optimizing the data updates Wrap-up
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Resources •
Joe Darlak of COMERIT, SAP NetWeaver BI and Portals 2010 conference (Orlando, Florida) Practical Tips to Improve Data Loading Performance and Efficiency in SAP NetWeaver by Up to 75%
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Training BW360 BW – Performance and Administration class
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7 Key Points to Take Home •
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Use the SAP NetWeaver BW statistics to find data loads that require optimization – target to optimize top 5-10 every month Use SE30 to analyze ABAP runtime for DataSources and transformations Review and implement the recommended database parameters for SAP NetWeaver BW Ensure that all SQL statements used in the data loading process are using indices and that statistics are calculated for the tables Make sure that the ABAP coding used in extraction exits and transformation is optimized Review and optimize the data models to avoid unnecessary processing Use parallel processing during data loading and updates 54
Your Turn!
How to contact me: Jesper Moselund Christensen
[email protected] 55
Disclaimer SAP, R/3, mySAP, mySAP.com, SAP NetWeaver®, Duet®, PartnerEdge, and other SAP products and services mentioned herein as well as their respective logos are trademarks or registered trademarks of SAP AG in Germany and in several other countries all over the world. All other product and service names mentioned are the trademarks of their respective companies. Wellesley Information Services is neither owned nor controlled by SAP.
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