How to determine the Join Order in an execution plan in Oracle

The join order in an execution plan is the order in which the optimizer decides to join tables together in a multi-table SQL statement. Determining the join order in an execution plan and knowing if it's optimal and how to correct it if it's not is a tricky proposition for most of us.
This video explains the simple set of rules the optimizer uses to determine the join order and provides two simple approaches to help you find the join order for both straightforward and complex plans. I also discuss why you don't always get an optimal plan and how to fix it.
TOC
What is the join order? 0:15
Optimizer rules for selecting the join order 1:00
How to determine the join order using depth-first search 2:30
How to find the join order from the outline of the plan 3:46
What causes suboptimal join orders, and how you can correct them 5:44

[@humayunhimu6045]

very informative and helpful! Thanks a lot , Maria!

[@michaeljones7674]

Great visuals to animate understanding. +OUTLINE can really help

[@redwisdome]

Thanks a lot Maria

[@albertogonzalez5114]

Quite useful, thanks!