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Ad: CBO Days 2012 – Final Agenda
The 11th and 12th of December and, therefore, the CBO Days in Zurich are approaching. Given the high quality of the speakers that accepted my invitation and the number of people that decided to attend the event, in my opinion it will be a blast! By the way, if you are interested in attending the [.....
Mi, Nov 28 2012
Ad: CBO Days 2012
The company I work for, Trivadis, is very pleased to organize, the 11th and 12th of December, an outstanding seminar with top guest speakers in Zurich. This year’s focus will be on the Oracle query optimizer, also known as a cost-based optimizer (CBO). The query optimizer is not only one of the most...
Do, Sep 27 2012
Index Scan with Filter Predicate Based on a Subquery
Most execution plans can be interpreted by following few basic rules (in TOP, Chapter 6, I provide such a list of rules). Nevertheless, there are some special cases. One of them is when an index scan, in addition to the access predicate, has a filter predicate applying a subquery. The following execution...
Mo, Feb 6 2012
Ad: The Oracle Query Optimizer 2-Day Seminar
The 31st of January and 1st of February 2012 I will present a 2-day seminar about the Oracle query optimizer in Ballerup (DK). The event is organized by Miracle A/S. The content, which is based on the chapters 2, 4, 5, 6, 9 and 10 of my book, is the following: Chapter 1 describes the life [...]
So, Dez 18 2011
Challenges and Chances of the 11g Query Optimizer
Challenges and Chances of the 11g Query Optimizer is the name of a presentation I gave at several events (e.g. Trivadis Performance Days, Oracle OpenWorld, DOAG Konferenz, UKOUG Conference) throughout 2011. Its abstract is the following: With every new release, the query optimizer is enhanced. Oracle...
Mo, Dez 12 2011
Impact of STATISTICS_LEVEL on Cardinality Feedback and Adaptive Cursor Sharing
The STATISTICS_LEVEL parameter controls a bunch of features. In addition to the documentation, also the V$STATISTICS_LEVEL view provides a list of the ones it controls. SQL> SELECT statistics_name, description, activation_level 2 FROM v$statistics_level 3 ORDER BY 3 DESC, 1; STATISTICS_NAME [...
Mo, Sep 19 2011
optimizer_secure_view_merging and VPD
At page 189 of TOP I wrote the following piece of text: In summary, with the initialization parameter optimizer_secure_view_merging set to TRUE, the query optimizer checks whether view merging could lead to security issues. If this is the case, no view merging will be performed, and performance could...
So, Sep 11 2011
IS NULL Conditions and B-tree Indexes
At page 383 of my book I wrote the following sentence (BTW, the same information is also provided by Table 9-3 at page 381): With B-tree indexes, IS NULL conditions can be applied only through composite B-tree indexes when several SQL conditions are applied and at least one of them is not based on IS...
Do, Feb 17 2011
DBMS_AUTO_SQLTUNE: ORA-01748 and Documentation Bugs
As of 188.8.131.52 a new package, DBMS_AUTO_SQLTUNE, is available for accessing and configuring Automatic SQL Tuning. The package provides three features: Execution of the Automatic SQL Tuning task (EXECUTE_AUTO_TUNING_TASK) Generation of a report showing the output generated by the Automatic SQL Tuning...
Mi, Okt 6 2010
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