Sorry for the delay in getting to this. I've still got a big backlog of questions.

The answer is that the statistics in the data dictionary are not updated until you explicitly re-gather them, and until then the optimizer is not influenced by the modifications.

Read your newsletter regarding the ALTER TABLE MONITORING feature. Does this affect optimizer plans during the day, and does it update the statistics in the data dictionary?

Heard great feedback on your San Francisco class. Would have loved to have attended.