Wednesday, July 19, 2006

Finding Information

QUESTION

Hi Robert,

I don't understand the meaning of any of the items on the query plan.

Is there some document that would explain what they are? If there is, where can I get it?

Thanks.

ANSWER

That's the best kind of question. Instead of sending me a query plan and asking me to interpret it for you, you're asking me for the means to do it yourself. Which is good because there is so much I don't understand about Oracle that I would have to study up to help you anyway.

Oracle Documentation

I love Oracle documentation. I can usually find what I want in there, complete with examples and explanations. So let's start there.

Once you have navigated to Oracle's documentation page, you'll want to select "View Library" and then go thorugh the searching page.

Choosing the right phrase can be tricky. In this case, try TKPROF, Query Plan, Execution Plan.



Searching with any of these three phrases points rather conclusively at the Oracle Performance Tuning Guide and Reference. Taking a look through it, it seems to have lots of information to get you started on how to understand the execution plans you see in the TKPROF output.

Ask Tom

The second thing I like to do is Ask Tom. He has answered 33,000 questions, meaning that in any case, my question was probably already asked. Sometimes his answers include links to other information.



Searching our three chosen phrases points to one Ask Tom article in particular that might be helpful.

Google

Sometimes I can google around to find articles on a topic. Normally I favour sources I trust, like Jonathan Lewis or something. In this case, googling found me this article:

Use EXPLAIN PLAN and TKRPOF To Tune Your Applications, by Roger Schrag

Still Stuck?

If you've gone through these sources and you still haven't found the information you're looking for, it's time for a degree of intrepidity.

I would certainly want to contact my fellow Oracle specialists. But rather than contact one individually with an open-ended question, I would post a message to a forum or message board, making sure to highlight what I had already looked for, what I had already found, and specifically how it came up short.

It is possible that the information I'm looking for has never been written. If so, that would be a great opportunity for me to do some research and make my own, new contribution to the Oracle community.

Comments:
Robert,

Based on the number of times I've found myself explaining this kind of thing, I think this'll prove really useful for a lot of people. Nice one.

Cheers,

Doug
 
You ought to add this to the Performance Tuning wiki.
 
Post a Comment

<< Home

This page is powered by Blogger. Isn't yours?