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Author Archives Optimizer Development Group

Will the Optimizer development team be at Oracle Open World?

The largest gathering of Oracle customers, partners, developers, and technology enthusiasts will happen in September when Oracle will host its annual user conference Open World in San Francisco and the Optimizer development group will be there! You wil…

Posted 24 July 2008 § Uncategorized ‡ Comments Off °

Why are some of the tables in my query missing from the plan?

We apologize for our brief hiatus from blogging. We’ve been busy working on improvements to the optimizer.In 10gR2, we introduced a new transformation, table elimination (alternately called “join elimination”), which removes redundant tables from a que…

Posted 26 June 2008 § Uncategorized ‡ Comments Off °

Oracle support keeps closing my TAR because I cannot provide a testcase, can you help?

The answer to this question is yes, as Oracle Database 11g provides a new diagnostic tool called SQL Test Case Builder. In this article, we explain what SQL Test Case Builder is, and how to use it with examples.Why SQL Test Case Builder?For most SQL pr…

Posted 14 March 2008 § Uncategorized ‡ Comments Off °

Upgrading from Oracle Database 9i to 10g: What to expect from the Optimizer

One of the most daunting activities a DBA can undertake is upgrading the database to a new version. Having to comprehend all of the new features and to deal with potential plan changes can be overwhelming. In order to help DBA’s upgrade from Oracle Dat…

Posted 26 February 2008 § Uncategorized ‡ Comments Off °

Displaying and reading the execution plans for a SQL statement

Generating and displaying the execution plan of a SQL statement is a common task for most DBAs, SQL developers, and preformance experts as it provides them information on the performance characteristics of a SQL statement. An execution plan shows the d…

Posted 07 February 2008 § Uncategorized ‡ Comments Off °

Improvement of AUTO sampling statistics gathering feature in Oracle 11g

Optimizer statistics in Oracle are managed via a pl/sql package, dbms_stats. It provides several pl/sql procedures to gather statistics for a table, schema, or a database. For example, gather_table_statistics is used to gather statistics on a table. Th…

Posted 22 January 2008 § Uncategorized ‡ Comments Off °

Outerjoins in Oracle

Since release 6, Oracle has supported a restricted form of left outerjoin, which uses Oracle-specific syntax. In 9i, Oracle introduced support for ANSI SQL 92/99 syntax for inner joins and various types of outerjoin. The Oracle syntax for left outerjoi…

Posted 11 December 2007 § Uncategorized ‡ Comments Off °

Why are there more cursors in 11g for my query containing bind variables?

Oracle introduced a new feature, adaptive cursor sharing, in 11g, to improve the plans that are selected for queries containing bind variables. This feature can result in more cursors for the same query containing bind variables. We’ll explain why in…

Posted 03 December 2007 § Uncategorized ‡ Comments Off °

UK Oracle User Group Conference Dec 3-6

This week the UK Oracle User Group will host their annual Conference and Exhibition at the International Convention Centre Birmingham. There will be over 330 sessions at the conference and the Optimizer will star in at least 5 of them. One you’ll reall…

Posted 01 December 2007 § Uncategorized ‡ Comments Off °

Welcome to our blog

This blog will be our groups opportunity to set the record straight on the Oracle Cost Based Optimizer, and the statistics that feed it. It will also give you the opportunity to post questions and have them answered by the team.

Posted 30 November 2007 § Uncategorized ‡ Comments Off °