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by needusername 3745 days ago
> it can often be hard to find people who can troubleshoot performance issues. Even highly skilled people face a black box when they work on improving query performance as the CBO is largely a black box that can change from version to version. Without a clear explanation of how the CBO actually makes decisions it's often a bit of a crapshoot when tuning queries.

This has not been my experience.
1 comments
wildmXranat 3745 days ago
What part of parent has not been your experience ?

I have experience parent's woes and more. That includes having Oracle staff in house doing in-person knowledge transfer. Experience says that Oracle will not provide a qualified person if we call for one as well. Sourcing from their own consultant pool is also a black box crap-shoot.

We also involved Dell and their support team to provide feedback and second opinion on Oracle CBO, query optimization and overall needed knowledge to use their Toad for Oracle performance tools. They literally stopped short of saying: yeah, you need people smarter than us for that.

I still think Oracle is a great product, but it's only fit for large organizations with bottomless budgets. I think we spent something north of $100K on Oracle's E-learning and that was probably the cheapest item on the list.

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needusername 3744 days ago
> What part of parent has not been your experience ?

We have several people in house (I know of 6) who can troubleshoot performance issues. For them the CBO is not a black box and they can explain what is happening and why.

I know of a local consulting company that has several very good people that you can "order". Said consulting company also offers very good CBO courses/workshops.

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chris_wot 3744 days ago
Really? I have a book on CBO performance troubleshooting from the foremost expert and even he says that he can't fully understand why the CBO does the things it does.

I doubt your in house experts fully understand the Oracle CBO. They may claim they do, but unless they have access to material that isn't public they can't possibly be able to diagnose the CBO fully.

You realise there are over a thousand hidden database parameters, right?

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needusername 3743 days ago
> Really? I have a book on CBO performance troubleshooting from the foremost expert and even he says that he can't fully understand why the CBO does the things it does.

> I doubt your in house experts fully understand the Oracle CBO. They may claim they do, but unless they have access to material that isn't public they can't possibly be able to diagnose the CBO fully.

Maybe. Let me put it this way, so far they could explain all CBO decisions where we had performance issues.

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