Summary
Symptom
The response times in your BW system are unsatisfactory.
Other terms
Update statistics, sample values, SAP_ANALYZE_ALL_INFOCUBES, performance
Reason and Prerequisites
For the MaxDB optimizer to select the correct access strategy, the statistics for the tables must be current and the sample size used to calculate the statistics for large tables must be optimal.
Solution- 1. See Note 808060 for information about setting the sample size or as of MaxDB Version 7.7.07.20, Note 1466524. Note 927882 provides detailed information about executing update statistics.
- 2. BW-specific report: SAP_ANALYZE_ALL_INFOCUBES
In rare cases in very large BW systems, a sample size of 5% or 10% may be insufficient. The required performance improvement may not have been implemented even after a conversion and another update statistics run.
In such cases, SAP Support will examine the generated statistics and decide whether they need to be generated with a sample size of more than 5%.
If they do, the estimated values are not changed in the "domain.tables" system table but are updated with the SAP_ANALYZE_ALL_INFOCUBES report instead.
In the report, the required sample size is specified in percent (%).
It may be useful to update the statistics based on a sample size of 100% with the SAP_ANALYZE_ALL_INFOCUBES report.
This increases the runtime of the statistics update accordingly.
Note:
If you want to use this procedure in your BW system for specific tables, a new update statistics run with DB13 will overwrite the statistics again.
To exclude a table from update statistics (explicitly using DB13 and implicitly), you must set the sample size for the relevant tables in the system table "domain.tables" to the value 0:
ALTER TABLE <table name> SAMPLE 0 ROWS
or
ALTER TABLE <table name> SAMPLE 0 PERCENT
Header Data
| Release Status: | Released for Customer |
| Released on: | 01.07.2010 10:19:17 |
| Master Language: | German |
| Priority: | Recommendations/additional info |
| Category: | Performance |
| Primary Component: | BW-SYS-DB-SDB BW MaxDB |
Affected Releases
Release-Independent
Related Notes
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