You can skip the first three sections of rambling burp and get straight to the nitty gritty at "The basic forms of Oracle data retrieval".

• Background
• Revision History
• Introduction to performance tuning
• General
• The need for tuning, a simple example
• Poor SQL or a slow server... who can we shout at?
• The basic forms of Oracle data retrieval
• full table scan
• index range scan
• index unique scan
• The oracle optimiser
• Introduction
• Table and Index statistics
• The rule based optimiser
• The cost based optimiser
• Obtaining the access plan for a statement
• Creating the necessary tables
• The Explain Plan
• Querying the plan tables
• Doing it the TOAD way
• Tuning a single statement
• Interpreting the explain plan
• Operation
• Rows Processed
• Bytes read
• Cost and it's true meaning
• Consolidation of statements
• Lateral thinking
• Full table scans - large and small tables
• Sort and merge operations
• Overriding the optimiser mode (hints)
• Identifying existing statements
• Useful values
• Useful performance views
• Useful statements
• Which schema or instance should I be tuning?
• Some do's and don'ts
• Finally...
• Credits
• Resources and Links