Archive for the ‘Troubleshooting’ Category

Using Bitmap Indexes Effectively

Thursday, May 29th, 2008

Recently I was reading this thread, "Trying to make use of bitmap indexes" on the Oracle Forum. Before I had finished a working example, Jonathan Lewis had posted his response which was on par with my thoughts. Since this is a topic I see frequently, I thought ...

Choosing An Optimal Stats Gathering Strategy

Wednesday, March 26th, 2008

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 ...

Awareness Test

Friday, March 21st, 2008

I came across this video the other day and I immediately thought of rule #3 from my Got Root Cause? post: "Be detail oriented, but do not become too obsessed with any one detail." Watch the video and see if you pass the Awareness Test. Most importantly, remember the punch line ...

ANSI Outer Joins And Lateral Views

Monday, February 18th, 2008

A few months ago the Oracle Optimizer Team did a blog post entitled Outerjoins in Oracle. In the Lateral View section of that post they go through some examples and discuss how a query is transformed with the ANSI outer join syntax. I thought it would be useful ...

Oracle 11g: Real-Time SQL Monitoring Using DBMS_SQLTUNE.REPORT_SQL_MONITOR

Sunday, January 6th, 2008

Many times a DBA wants to know where a SQL statement is in its execution plan and where the time is being spent. There are a few ways to find out this information, but an 11g new feature makes gathering this information extremely easy. Oracle 11g Real-Time SQL Monitoring ...

Oracle Myth Busting: Show, Don’t Tell

Sunday, December 16th, 2007

Richard Foote has recently started blogging (as of December 11th) and one of his recent posts discusses Oracle Myths and Information Pollution. I find this topic very interesting as I'm always amazed at the number of people who make changes to their production database based on the results from ...

Oracle Optimizer Development Team Starts A Blog

Wednesday, December 5th, 2007

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. ...

Troubleshooting Bad Execution Plans

Wednesday, November 21st, 2007

One of the most common performance issues DBAs encounter are bad execution plans. Many try to resolve bad executions plans by setting optimizer related parameters or even hidden underscore parameters. Some even try to decipher a long and complex 10053 trace in hopes to find an answer. ...