|Oracle 9i Performance Doubts [message #64827]
|Tue, 17 February 2004 04:04
Registered: October 2000
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)
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