Oracle User Group DBMS SIG group meeting

Today I had a chance to see Jonathan Lewis on UKOUG DBMS SIG meeting, I have read his book and wanted to see him in a real life. Jonathan did very interesting presentation about Cost Based Optimiser.

For me it was a surprise how migration from one Oracle version to another can affect your application performance and lead to disaster without careful planing and testing. We are going to migrate our application form Oracle 9i to Oracle 10g R2 and it seems that this migration will not be so easy as I assumed.