Wednesday, March 28, 2012

(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:

Cost-Based Optimizer Basics

When it comes to writing efficient queries there are a few key concepts that need to be understood. Although it is called a cost-based optimizer it is actually not the cost we need to focus on primarily to understand why the optimizer takes certain decisions. In this webinar these key concepts will be highlighted and explained along with some live demos. We will see why it is crucial that the optimizer's picture of the data fits reality, why cardinality and selectivity estimates matter so much and which key concepts the optimizer's model surprisingly doesn't cover (yet). This also means that you as a human being sometimes know much more about the data and may need to lead the optimizer into the right direction.

2. I'll be giving essentially the same session for the DOAG database SIG on Friday, the 11th May 2012 11:00 (Germany).

This webinar is only available to DOAG members I believe, but if you are a member then it is free. This one I'll be giving in German.

The number of (virtual) seats seems to be limited, so you might want to get in touch with the contact details mentioned below:

Julia Kasprzak,
DOAG Geschäftsstelle

Here is the link to the DOAG website and the session details in German:

Cost-Based Optimizer Grundlagen

Wenn es darum geht, effizientes SQL zu schreiben, gibt es einige wenige Schlüsselkonzepte, die zu verstehen sind. Obwohl es "kostenbasierter Optimizer" genannt wird, sind es eben nicht primär die Kosten, auf die wir schauen müssen, um zu verstehen, warum der Optimizer bestimmte Entscheidungen getroffen hat. In diesem Webinar werden diese Schlüsselkonzepte beleuchtet und anhand von einigen Live-Demonstrationen erklärt. Wir werden sehen, warum die Kardinalitäts- und Selektivitätsabschätzungen des Optimizers so elementar wichtig sind und welche Schlüsselkonzepte der Optimizer überraschenderweise derzeit (noch) nicht berücksichtigt. Dies bedeutet auch, dass wir manchmal wesentlich mehr über unsere Daten und Applikation wissen als der Optimizer und daher ihn in die richtige Richtung lenken müssen.

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