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Oracle 9i Performance Doubts [message #64827] Tue, 17 February 2004 04:04 Go to next message
Messages: 104
Registered: October 2000
Senior Member
Hi All,

IS there any command or method to find out what is the maximum IO permitted on unix(SUN and HP) and Linux and NT platforms. optimizer_index_caching(<100) which favours Nested loops and Optmizer_index_cost_adj(<100) which favours Index scans.Suppose If set db_file_multiblock_read_count=32 still I am seeing the good performance.that is still it is using Index scans. My next question is db_file_multiblock_read_count=32 help in fetching index blocks with less IO.

My third question is Which Parameters I have to look in statspack to find the diffrence for setting of these parameters(optimizer_index_caching and Optmizer_index_cost_adj). and also

please advice me what more parameters I have set to use to drive oracle for better performance.Since I have only control from database not much from application.Most of the things driven from java/corba stuff.
2)optimizer_mode= first rows Since it fetches results fast for fewer records may go suboptimal plans and all rows favours full table scans (advice me here)
3) pga_aggregate_target=200m
4) workarea_size_policy=auto.

What more parameters I have to set in the initalization paramerts.

and 4th Question is in Donlad Burleson articles says that setting log_buffer > 4M is of not much use.


 But I may predict the redolog space requests and redo allocation retries will increase if I am reducing redolog buffer u'r advice on this.

Finally in rollback segments we were assigning bigger rollback segment for any large jobs how the same thing is taken care in undo_tablespace. If I am setting too much undo_retention this will be applicable for all the undo segments which I feel waste of space.I am quite curious to know is anyway we can provide large chunk of space for paritcular undo segment.

Thanks and Regards


Re: Oracle 9i Performance Doubts [message #64828 is a reply to message #64827] Tue, 17 February 2004 05:59 Go to previous message
Messages: 1089
Registered: May 2002
Senior Member
Nice questions Prasad.
answered here --> Server forum


[Updated on: Fri, 18 February 2005 23:32]

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