Understanding System Statistics

by Jonathan Lewis

Understanding the optimizer’s use of system statistics can make a big difference when migrating to a new version of the Oracle Database.

What is the most important component of the Oracle Database engine? My vote goes to the optimizer. Everything the database does is SQL, and every piece of SQL has to be translated into something that can work efficiently. Whatever you do with your data, the optimizer gets involved.

http://www.oracle.com/technology/pub/articles/lewis_cbo.html