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Friendly Reminder - Free Webinar

This is just a friendly reminder that tomorrow my free Webinar on Cost-Based Optimizer Basics will take place at

(Virtual) Public Appearances - Free Webinars

I'll be presenting at two upcoming webinars:

1. "Oracle Cost-Based Optimizer Basics" hosted by on Wednesday, 11th April 2012 16:00 (UK Time).

In this session I'll explain the key concepts that influence the decisions of the Oracle Cost-Based Optimizer most. If you want to understand the key concepts about how to write efficient queries and why the optimizer sometimes might not come up with a reasonable execution plan, then this session is for you.

Note that the webinar is free and registrants will receive a recording afterwards. Here is the link to the official landing page. Thanks to for hosting this session.

Here is an abstract of the session:

Just a short note that as already announced last week the second part of the post on how to control Dynamic Sampling activity has been published on

You can read there about the (not so much known) DYNAMIC_SAMPLING_EST_CDN hint, the new Dynamic Sampling auto adjustment feature introduced in release 11.2 and other interesting details.

This is just a short note that the next part of my Dynamic Sampling series has been posted on

This time I highlight how to configure Dynamic Sampling - the first part focusing on the available session/statement levels. The next part will be posted soon and explains some other important concepts regarding Dynamic Sampling behaviour.

Unfortunately these topics are not covered very well by the official documentation. In fact the best coverage used to be in the documentation of the initial release that included Dynamic Sampling (9iR2). You can find the link to that old documentation version in the article over there.

This is just a short notice that the second part of the introduction to Dynamic Sampling has been posted on