Recently the Oracle Optimizer Development Team put out a White Paper entitled Upgrading from Oracle Database 9i to 10g: What to expect from the Optimizer. This paper discusses the main differences between 9i and 10g in the subject area of the Optimizer and Statistics. As G.I. Joe said, “Now we know! And knowing is...
Since the introduction of the Cost Based Optimizer (CBO) in Oracle 7.0, people have been both fascinated and terrified by it and the statistics that feed it. There has long been a belief that a degree in witchcraft or black magic is required to successfully work with the CBO. Some people feel this shroud...
In the Real-World Performance Roundtable, Part 2: The Optimizer, Schema Statistics, SQL Tuning at Oracle OpenWorld 2006, I worked an example of how the optimizer can have difficulty estimating the correct cardinality when there is data correlation. (The Zodiac example can be found on pages 46-49 of the presentation.) In Oracle 11g, there has...