BW Query Performance
Question:
1. What kind of tools are available to monitor the
overall Query Performance?
Answers:
-
BW Statistics
-
BW Workload Analysis in ST03N (Use Export Mode!)
-
Content of Table RSDDSTAT
Question:
2. Do I have to do something to enable such tools?
Answer:
-
Yes, you need to turn on the BW Statistics:
RSA1, choose Tools -> BW statistics for InfoCubes
(Choose OLAP and WHM for your relevant Cubes)
Question:
3. What kind of tools are available to analyse a specific
query in detail?
Answers:
-
Transaction RSRT
-
Transaction RSRTRACE
Question:
4. Do I have a overall query performance problem?
Answers:
-
Use ST03N -> BW System load values to recognize the problem.
Use the
number given in table 'Reporting - InfoCubes:Share of
total time (s)'
to check if one of the columns %OLAP, %DB, %Frontend
shows a high
number in all InfoCubes.
-
You need to run ST03N in expert mode to get these values
Question:
5. What can I do if the database proportion is high
for all queries?
Answers:
Check:
-
If the database statistic strategy is set up properly for
your DB platform
(above all for the BW specific tables)
-
If database parameter set up accords with SAP Notes and SAP
Services (EarlyWatch)
-
If Buffers, I/O, CPU, memory on the database server are exhausted?
-
If Cube compression is used regularly
-
If Database partitioning is used (not available on all DB
platforms)
Question:
6. What can I do if the OLAP proportion is high for
all queries?
Answers:
Check:
-
If the CPUs on the application server are exhausted
-
If the SAP R/3 memory set up is done properly (use TX ST02
to find
bottlenecks)
-
If the read mode of the queries is unfavourable (RSRREPDIR,
RSDDSTAT,
Customizing default)
Question:
7. What can I do if the client proportion is high
for all queries?
Answer:
-
Check whether most of your clients are connected via a WAN
Connection and the amount of data which is transferred is rather high.
Question:
8. Where can I get specific runtime information for
one query?
Answers:
-
Again you can use ST03N -> BW System Load
-
Depending on the time frame you select, you get historical
data or current data.
-
To get to a specific query you need to drill down using the
InfoCube name
-
Use Aggregation Query to get more runtime information about
a
single query. Use tab All data to get to the details.
(DB, OLAP, and Frontend time, plus Select/ Transferred
records,
plus number of cells and formats)
Question:
9. What kind of query performance problems can I recognize
using ST03N
values for a specific query?
Answers:
(Use Details to get the runtime segments)
-
High Database Runtime
-
High OLAP Runtime
-
High Frontend Runtime
Question:
10. What can I do if a query has a high database runtime?
Answers:
-
Check if an aggregate is suitable (use All data to get values
"selected records to transferred records", a high number
here would
be an indicator for query performance improvement using
an aggregate)
-
Check if database statistics are update to data for the
Cube/Aggregate, use TX RSRV output (use database check
for statistics and indexes)
-
Check if the read mode of the query is unfavourable - Recommended
(H)
Question:
11. What can I do if a query has a high OLAP runtime?
Answers:
-
Check if a high number of Cells transferred to the OLAP (use
"All data" to get value "No. of Cells")
-
Use RSRT technical Information to check if any extra OLAP-processing
is necessary (Stock Query, Exception Aggregation, Calc.
before
Aggregation, Virtual Char. Key Figures, Attributes in
Calculated
Key Figs, Time-dependent Currency Translation)
together with a high number of records transferred.
-
Check if a user exit Usage is involved in the OLAP runtime?
-
Check if large hierarchies are used and the entry hierarchy
level is
as deep as possible. This limits the levels of the
hierarchy that must be processed. Use SE16 on the inclusion
tables and use the List of Value feature on the column
successor
and predecessor to see which entry level of the hierarchy
is used.
- Check if a proper index on the inclusion table
exist
Question:
12. What can I do if a query has a high frontend runtime?
Answers:
-
Check if a very high number of cells and formattings are
transferred
to the Frontend ( use "All data" to get value "No. of
Cells") which
cause high network and frontend (processing) runtime.
-
Check if frontend PC are within the recommendation (RAM,
CPU Mhz)
-
Check if the bandwidth for WAN connection is sufficient
Self-Test Question
Sap Business Warehouse (BW) provides:
a. Powerful Information Analysis.
b. Rich Business Content with different Information Models,
reports and extractors.
c. End-to-end data warehousing Solutions.
d. SAP R/3 Logistics
e. Advance Planner and Optimizer
Correct Answer:
a, b, c |
SAP BW Tips
|