How do you interpret a query's explain plan?

Question

When attempting to understand how a SQL statement is executing, it is sometimes recommended to look at the explain plan. What is the process one should go through in interpr

Answer 1

Really for issues like these, the best thing to do is ASKTOM. In particular his answer to that question contains links to the online Oracle doc, where a lot of the those sorts of rules are explained.

One thing to keep in mind, is that explain plans are really best guesses.

It would be a good idea to learn to use sqlplus, and experiment with the AUTOTRACE command. With some hard numbers, you can generally make better decisions.

But you should ASKTOM. He knows all about it :)