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oracle sequence is causing high cpu usage? [message #277726]

Wed, 31 October 2007 05:34

dba4bank
Messages: 49
Registered: October 2007
Location: TURKEY

Member

I have a oracle 10G database on windows server 2003
oracle sequence is causing high cpu usage.it is sometime % 86 percent.

I am issuing this command from forms "SELECT seqno.NEXTVAL FROM DUAL"

[Updated on: Wed, 31 October 2007 06:36]

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Re: oracle sequence causing high cpu usage [message #277729 is a reply to message #277726]

Wed, 31 October 2007 05:37

Michel Cadot
Messages: 68665
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Prove what you say.

Read and follow OraFAQ Forum Guide and How to Identify Performance Problem and Bottleneck and provide the requested information.

Regards
Michel

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Re: oracle sequence is causing high cpu usage? [message #278183 is a reply to message #277726]

Fri, 02 November 2007 05:21

zoltanp
Messages: 58
Registered: March 2005
Location: Hungary

Member

Have you set the cache parameter of the sequence?

The nocache or low cache parameter may cause high cpu usage.

Zolt�n Patalenszki

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Re: oracle sequence is causing high cpu usage? [message #278195 is a reply to message #278183]

Fri, 02 November 2007 06:09

Michel Cadot
Messages: 68665
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Quote:

The nocache or low cache parameter may cause high cpu usage.

It may cause waits but I was not aware it may cause high cpu usage.
Can you provide where you get this information or how to show it?

Regards
Michel

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Re: oracle sequence is causing high cpu usage? [message #278206 is a reply to message #278195]

Fri, 02 November 2007 06:48

zoltanp
Messages: 58
Registered: March 2005
Location: Hungary

Member

I think that it may cause.
The nocache parameter caused bottleneck in our application
some years ago and the cache parameter help it.
I think that generating sequence element is not only I/O operation.

Sorry, but I can't prove but
Dba4bank will probe it, if they want.

Regards
Zolt�n Patalenszki

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Re: oracle sequence is causing high cpu usage? [message #278229 is a reply to message #278206]

Fri, 02 November 2007 07:50

Michel Cadot
Messages: 68665
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Quote:

The nocache parameter caused bottleneck in our application

I concur but this is because of locks and not cpu usage.

Regards
Michel

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Re: oracle sequence is causing high cpu usage? [message #283794 is a reply to message #278229]

Wed, 28 November 2007 03:00

dba4bank
Messages: 49
Registered: October 2007
Location: TURKEY

Member

ı already used high cache parameter.

thx for interested

regards

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Re: oracle sequence is causing high cpu usage? [message #284088 is a reply to message #277726]

Wed, 28 November 2007 16:23

Kevin Meade
Messages: 2103
Registered: December 1999
Location: Connecticut USA

Senior Member

I have seen two situations where sequences have cause increased resource consumption and delays in processing. for what it is worth:

1) as was indicated, nocache, or low cache value. Consider that a cache size of zero means that for each value selected from the sequence, an recursive update must be made to the underlying sequence table. You can see this update as sql in v$sqlarea. If you do lots of sequence number gets, you will have lots of updating. this is in fact one of the four problems of a current system I am working on that is having CPU issues and spikes.

2) .NET or 3GL or front end tool doing sequence number gets across the network. Not necessarily a CPU cost, but can really slow down an app because each sequence number get may be coded in that app as a network round trip.

good luck. Kevin

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