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Multiple sessions in a single instance and performance [message #224411] Wed, 14 March 2007 03:28 Go to next message
subratd
Messages: 12
Registered: March 2007
Junior Member
I would like to know if having large number of sessions in a single oracle instance hampers performance. If so, then how?
Re: Multiple sessions in a single instance and performance [message #224440 is a reply to message #224411] Wed, 14 March 2007 05:27 Go to previous messageGo to next message
martijn
Messages: 283
Registered: December 2006
Location: Netherlands
Senior Member
It largly depends on what those sessions are doing.
Re: Multiple sessions in a single instance and performance [message #224443 is a reply to message #224440] Wed, 14 March 2007 05:32 Go to previous messageGo to next message
subratd
Messages: 12
Registered: March 2007
Junior Member
They are doing dml operations.
Re: Multiple sessions in a single instance and performance [message #224450 is a reply to message #224443] Wed, 14 March 2007 05:42 Go to previous messageGo to next message
martijn
Messages: 283
Registered: December 2006
Location: Netherlands
Senior Member
ah...
If they all do something like "select * from <small_table>" it probably isn't a problem.

However if they all perform querys with lots of joins, using functions, ..... it will have impact on your performance.

I think what I'm trying to say is : The question is somewhat difficult to answer, since we don't know much about the system/database/type of query's/etc.

Maybe you can tell us what the underlying problem is. Maybe we can give an answer to that Smile
Re: Multiple sessions in a single instance and performance [message #224509 is a reply to message #224450] Wed, 14 March 2007 08:31 Go to previous message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
In general, idle sessions aren't much of a problem. They will all have been allocated a certain amount of memory, so a very large number of sessions can cause performance degredation.

What you need to think about is the total amount of work being performed on the Db, rather than the number of individual sessions.
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