In this free tutorial you will learn how to generate and read (interpret) an execution plan in Oracle Databases. See more FREE Oracle Tuning tutorials at http://skillbuilders.com/free-oracle-tutorials.
Understanding what the Oracle Database does with your SQL is essential to tuning - and the execution plan is the key.
Oracle Certified Master DBA John Watson will provide a brief introduction (4 minutes) - which includes John's tuning methodology, then demonstrate EXPLAIN PLAN, SQL*Plus AUTOTRACE and DBMS_XPLAN.DISPLAY_CURSOR. In the tutorial, John will teach you:
- How to read an execution plan
- Find the 1st step in the plan
- Decipher the order of the steps in the plan
- That EXPLAIN PLAN can be very misleading
Prerequisites: To get the most from this tutorial, you should:
1 Know how to code SQL
2 Be familiar with SQL*Plus
3 Know - in very general terms - what an execution plan is.
4 Have a basic understanding of the Library Cache (this is where Oracle Database stores parsed SQL statements)
5 Have a basic understanding of the Cost Based Optimizer (this is the part of the database that parses your SQL, creates an execution plan. Hopefully the correct - most efficient - plan).