I have recently been called onto a client site where they are having some
performance issues with an OLTP db.
If I outline the situation you will see some of the obvious problems, but I
having a couple of problems identifying the reason for differences in the
execution path of a couple of important queries and was wandering if anyone
knew of implementation difference between Enterprise Edition and Server
regarding the CBO or any CBO bugs in an unpatched install of 8.1.6.0.
Environment
Development Instance
Quad 400MHz NT server with Oracle 8i 8.1.6.0 EE, 1.5GB mem and 2 disks.
To be Production instance
Single 933MHz NT server with Oracle8i 8.1.6.0 8 disks in a RAID 1 stripe.
Instance data the same and all analyzed.
Init parameters the same.
queries involve outer joins between 4 small and one large table.
Run time on development is 5 seconds. On the "go live" server I have brought
it down to 20secs from 2 minutes by increasing the sort_area_size.
I am looking at reducing hash_area_size on the production instance to
sort_area_size as it appears to be favouring a hash join over nested loops.
I have limited access to the client and time availavble so want to avoid
10053 traces at present.
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Author: Allan Robertson
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