Database Statistics During ODS Activation Applies to: SAP BW (3.5) / SAP BI (7.0). For more information, visit the EDW homepage Summary ODS Activation step periodically recalculates the statistics. This can be a overhead if the activation step is critical. In order to suppress the statistics step the document can be referred. The document also mentions the need for statistics. Author: Srivatsan.S Company: Infosys Technologies Limited Created on: 24 Feb 2011 Author Bio Srivatsan is working with Infosys Technologies Limited. He has got rich experience in implementation of various projects in both SAP BW 3.5 and SAP Bi 7.0. 2011 SAP AG 1
Table of Contents Scenario:... 3 Overview on Database Statistics:... 3 Ignoring Statistics Recalculation & Resetting:... 3 Procedure to Ignore Statistics Recalculation:... 3 Procedure to Reset the Statistics Settings:... 5 Statistics Status During the above Process:... 6 Old Statistics:... 6 Disadvantages of Database Statistics:... 6 Related Content... 7 Related Content... 7 Disclaimer and Liability Notice... 8 2011 SAP AG 2
Scenario: This scenario occurred during the production support activity for our retail client. The timelines for the load completion is very critical for our account since the dependencies are more. One such situation occurred where the activation step for an ODS was stuck for a very long time. On checking the Activation Job Logs, we found that the job was performing the statistics recalculation as shown in the screenshot below. This paves way for the document on Database Statistics during ODS Activation. Overview on Database Statistics: During the ODS activation process the statistics are generated for both 00 (Active table) and 40 (New Table) tables of the ODS. This can under circumstances slow down the activation process. However this step is essential for query performance over the ODS. Note: The Statistics recalculation step does not trigger every time the activation job is executed. This is not a periodic event as well. This process starts when the statistics seemed to have been corrupted. Ignoring Statistics Recalculation & Resetting: The statistics recalculation step at times causes an overhead during critical data load activation processes. For example: Consider the scenario where the ODS data has to be pushed further to a series of Infocubes on time and the process is stuck in the activation step of the ODS. The Statistics step can be ignored using the Report: RSSM_SUPPRESS_STATISTICS Note: The above program mentioned RSSM_SUPPRESS_STATISTICS is to be used during the activation process. Also note that the statistics will have to be manually generated if this option is used. Procedure to Ignore Statistics Recalculation: 1. Go to SE38 and type the program RSSM_SUPPRESS_STATISTICS and Execute. 2. The program RSSM_SUPRESS_STATISTICS has option to enter the ODS name and it gives 2 checkboxes. The check boxes work according to the following logic. 2011 SAP AG 3
1. Check DB St. Deactivated before Act and Check DB St. Deactivated after Act: This option will suppress the Statistics step totally for the particular ODS. 2. Check DB St. Deactivated before Act and Uncheck DB St. Deactivated After Act: This option will suppress the Statistics step before the Activation Step and Enable it after the Activation is complete.(recommended) 3. Uncheck DB St. Deactivated Before Act and Check DB St. Deactivated After Act: This option will suppress the Statistics step after the Activation Step (not recommended as it would have no effect). 4. Uncheck DB St. Deactivated Before Act and Uncheck DB St. Deactivated After Act: This option will enable the Statistics step totally for the particular ODS. Let us proceed with Step 2: 3. Once the above step is executed with ODS name the following screen appears: 4. This program basically changes the fields of the Table RSODSSETTINGS. 2011 SAP AG 4
Procedure to Reset the Statistics Settings: 1. Go to SE38 and type the program RSSM_SUPPRESS_STATISTICS and Execute 2. Enter the ODS name and Execute. Please note that the both the check boxes are to be unchecked. 3. Once the above step is executed the following screen appears: 2011 SAP AG 5
4. The changes are reverted back in the Table RSODSSETTINGS Statistics Status During the above Process: The Statistics will not be generated once the above process is followed. It has to be manually generated from DB02 for the particular ODS. Old Statistics: The performance of the old statistics cannot be conclusive as the decision factor is on how well the current data set is represented. Disadvantages of Database Statistics: Every change happening on the statistics can cause changes to the optimizer. In most of the cases regular update of statistics will have a positive effect on performance. 2011 SAP AG 6
Related Content SAP Community Network Forums: Using RSSM_SUPPRESS_STATISTICS... SAP Community Network Forums» Enterprise Information Management» Enterprise Information Management - General Activate Data in ODS Objects For more information, visit the EDW homepage 2011 SAP AG 7
Disclaimer and Liability Notice This document may discuss sample coding or other information that does not include SAP official interfaces and therefore is not supported by SAP. Changes made based on this information are not supported and can be overwritten during an upgrade. SAP will not be held liable for any damages caused by using or misusing the information, code or methods suggested in this document, and anyone using these methods does so at his/her own risk. SAP offers no guarantees and assumes no responsibility or liability of any type with respect to the content of this technical article or code sample, including any liability resulting from incompatibility between the content within this document and the materials and services offered by SAP. You agree that you will not hold, or seek to hold, SAP responsible or liable with respect to the content of this document. 2011 SAP AG 8