Archive for the ‘Troubleshooting’ Category
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. ...
Posted in Execution Plans, Optimizer, Oracle, Performance, Statistics, Troubleshooting | 8 Comments »
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. ...
Posted in Execution Plans, Optimizer, Oracle, Performance, SQL Tuning, Statistics, Troubleshooting | 23 Comments »
Friday, October 26th, 2007
From time to time I get a little writer's block and sometime search for topics to blog about. I thought, what better way to get ideas for blog posts than to ask the readers of this blog. Here is your chance to influence the topic of upcoming ...
Posted in Oracle, Performance, Troubleshooting | 2 Comments »
Tuesday, October 16th, 2007
Here is some code to display the HIGH_VALUE/LOW_VALUE columns from USER_TAB_COL_STATISTICS which are stored as RAW datatypes.
[sourcecode language='sql']create or replace function display_raw (rawval raw, type varchar2)
return varchar2
is
cn number;
cv varchar2(32);
cd ...
Posted in Execution Plans, Optimizer, Oracle, Statistics, Troubleshooting | 1 Comment »
Monday, October 1st, 2007
Andrew Holdsworth, the Senior Director of the Real-World Performance Group, will be having two presentation sessions at Oracle OpenWorld 2007, in addition to the Real-World Performance Group Roundtable session. The first presentation is Current Trends in Database Performance and the second one is When to Use the Appropriate Database ...
Posted in Oracle, Performance, Troubleshooting | No Comments »
Monday, April 23rd, 2007
In my previous post, Bind Variables, I discussed why using bind variables is one of the most important fundamentals in engineering scalable database applications. I briefly touch on the point that cursor management is also very important. In this post I will go into why this is important, ...
Posted in Performance, Troubleshooting | No Comments »
Monday, March 5th, 2007
Many of us have been in a situation where the performance of our Oracle database has degraded. Ultimately, we are looking to correctly diagnose the root cause and resolve the performance issue. This is frequently easier said than done. I'd like to offer a few thoughts ...
Posted in Troubleshooting | 2 Comments »