on 09-18-2009 9:37 AM
Hello,
a few weeks ago, I got a case of performance problems. I have analyzed with SAP Kommando Monitor and found a strange behaviour in intervalls of 5 minutes.
The select statements are asking for few rows, mostly 1 to 10. They have a selectivity of 100 % and they need 10 to 20 seconds.
We are using MAXDB 7.6.04.14, Data_Cache hit ratio ist at 99,8 %, Cat_Cache hit ratio at 98 %. There are no lock waits and no suspends.
Database analyzer shows no critical information.
What reason can be possible for this situation? Waits for Tasks?
Best Regards
Andreas
Hello Andreas,
this doesn't sound as if there is a problem with the optimizer but rather that the database needs to wait for resources.
To get further information, enable time measurement (x_cons <sid> time enable) and set the dbanalyzer interval to 120 or even 60 seconds to get more data samples within the problematic timeframe.
regards,
Lars
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Hello Lars,
I have enabled x_cons. Where can I find the logs?
I have startet the analyzer with an intervall of 60 seconds. Now I can see about 10 processes of one UKT waiting for CPU in state command wait and 1 process in state vbegexcl.
I can see nothing special in 5 minutes intervalls,
Regards
Andreas
The x_cons command I posted does not write it's own logs.
All it does is to switch on time measurement within the database kernel.
These additional time information are also evaluated by DBanalyzer.
And of course you wouldn't expect to see something in the DBAnalyzer logs if the problem does not occur.
to move on here I propose to wait until the hanging situation reoccurs and keep the analysis settings as they are right now.
Once the situation reoccurs, open a support message to have this analyzed.
The absence of DBAnalyzer warning messages does not mean that there are no useful information available. Especially checking the expert log files sometimes brings additional insight.
best regard,
Lars
Hello,
I can see the hanging situation in the kommando monitor. So it should be out of SAP through dbadaslib to MAXDB. The time measurement of the kommando monitor is in the database, isn't it? So the SAP ABAP component can not be involved.
I opened this threat to see, if anyone else have had the problem already.
I think it will be best to open a customer message in SAP Service marketplace to analyze the problem.
Best regards
Andreas
> I can see the hanging situation in the kommando monitor. So it should be out of SAP through dbadaslib to MAXDB. The time measurement of the kommando monitor is in the database, isn't it? So the SAP ABAP component can not be involved.
What exactly do you see in the command monitor?
It just shows the execution time statistics for the logged statements, but no hanging situations...
In general: if there is no change in the users response times - then there is no performance problem.
And if there is such a change, then we would see it in the ABAP performance traces as well.
> I think it will be best to open a customer message in SAP Service marketplace to analyze the problem.
Yep, taking a look into this directly may be much more efficient.
regards,
Lars
Hello Lars,
I can see every five minutes at exactly one second all sql-Statements running 10 to 15 seconds. The performance of the transaction is also bad.
We have installed a new version of monitoring tool an were able to activate the monitoring again, without this problem.
Best Regards
Andreas
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