Hotsos Symposium Speaker – Wolfgang Breitling

Mr. Breitling is a prior Hotsos Symposium presenter.


Wolfgang BreitlingWolfgang Breitling was born in Stuttgart, Germany, and studied mathematics, physics and computer sciences at the University of Stuttgart. Following several years as systems programmer for IMS and later DB2 databases on IBM mainframes, he got on the project to implement Peoplesoft on Oracle. In 1996, he became an independent consultant specializing in administering and tuning Peoplesoft on Oracle. The particular challenges in tuning Peoplesoft, with often no access to the SQL, motivated him to explore Oracle's cost-based optimizer in an effort to better understand how it works and use that knowledge in tuning. He has shared the findings from this research in papers and presentations at IOUG, UKOUG, local Oracle user groups, and other conferences and newsgroups dedicated to Oracle performance topics.

Presentation Title

Tuning by Cardinality Feedback


This presentation discusses a method of tuning which is based on the premise that whenever the CBO chooses a bad plan it can be traced back to an error in the estimation of the cardinality of one or more row sources. Tuning by cardinality feedback thus looks at discrepancies between estimated and real row source cardinalities of an execution plan and attempts to find ways to correct the CBO.s error in estimation, ultimately trusting it to find a better plan based on the corrected, more accurate estimates.

The Method will be demonstrated on examples taken from a production setting. The results are also compared to tuning with hints and to profiles generated by dbms_sqltune.

Presentation Materials

Presentation materials are available online to attendees only. Wolfgang's materials can be found on the Hotsos portal. Attendees may use their portal ids to log in rather than email addresses to retrieve the documents.


The speaker schedules can be found at the following links: