Control file sequential read wait event
I recently came across an interesting scenario when troubleshooting performance issues on a particular application. It's a Visual Basic application run behind an Excel spreadsheet. It makes a stored procedure call that dynamically creates a table based on a given criteria, then drops it after the results are returned to the client via ref cursor. This is generally not an approach I favor; however, it was the only way I saw to meet the requirements.
One particular DDL statement took over 21 minutes to run. However, the DDL itself ran to completion in slightly under 2 minutes. The trace reveals a high number of control file sequential reads during the interaction between Excel and Oracle. This event immediately goes away if I were to kill the session.