BC remote Oracle DBA - Call (800) 766-1884  
Oracle Consulting Oracle Training Development

Remote DBA

Remote DBA Plans  

Remote DBA Service

Remote DBA RAC

Remote DBA Oracle Home
Remote DBA Oracle Training
Remote DBA SQL Tuning Consulting
Remote DBA Oracle Tuning Consulting
Remote DBA Data Warehouse Consulting
Remote DBA Oracle Project Management
Remote DBA Oracle Security Assessment
Remote DBA Unix Consulting
Burleson Books
Burleson Articles
Burleson Web Courses
Burleson Qualifications
Oracle Links
Remote DBA Oracle Monitoring
Remote DBA Support Benefits
Remote DBA Plans & Prices
Our Automation Strategy
What We Monitor
Oracle Apps Support
Print Our Brochure
Contact Us (e-mail)
Oracle Job Opportunities
Oracle Consulting Prices





Remote DBA services

Remote DBA Support

Remote DBA RAC

Remote DBA Reasons

Remote Oracle Tuning

Remote DBA Links

Oracle DBA Support

Oracle DBA Forum

Oracle Disaster

Oracle Training

Oracle Tuning

Oracle Training

 Remote DBA SQL Server

Remote MSSQL Consulting

Oracle DBA Hosting

Oracle License Negotiation









Oracle Tips 

by Burleson Consulting

The Data Warehouse Development Life Cycle

Parallelism And Oracle Data Warehousing
Freelists And Oracle Parallel Server Contention

Freelists are especially important for Oracle data warehouses that experience a high volume of localized update activity. A freelist is the parameter used when more than one concurrent process is expected to access a table. Oracle keeps one freelist for each table in memory, and uses the freelist in order to determine what database block to use when an SQL INSERT occurs. When a row is added, the freelist is locked. If more than one concurrent process is attempting to insert into your table, one of the processes may need to wait until the freelist has been released by the previous task. To see if adding a freelist to a table will improve performance, you will need to evaluate how often Oracle has to wait for a freelist. Fortunately, Oracle keeps a V$ table called V$WAITSTAT for this purpose. The following query example tells you how many times Oracle has waited for a freelist to become available. As you can see from the following query, Oracle does not tell you which freelists are experiencing the contention problems:


--------------- ------------
free list 83

Here, we see that Oracle had to wait 83 times for a table freelist to become available. This could represent a wait of 83 times on the same table or perhaps a single wait for 83 separate tables. We have no idea. While 83 may seem to be a large number, remember that Oracle may perform hundreds of I/Os each second, so 83 may be quite insignificant to the overall system. In any case, if you suspect that you know which table’s freelist is having the contention, the table can be exported, dropped, and redefined to have more freelist. While an extra freelist consumes more of Oracle’s memory, additional freelists can help the throughput on tables that have lots of inserts. Generally, you should define extra freelists only on those tables that have many concurrent update operations. Now, let’s take a look at some table definitions and see if we can infer the type of activity that will be taking place against the tables. Listings 7.1 and 7.2 each present a table definition.

This is an excerpt from "High Performance Data Warehousing".

If you like Oracle tuning, you may enjoy the book Oracle Tuning: The Definitive Reference , with over 900 pages of BC's favorite tuning tips & scripts. 

You can buy it directly from the publisher and save 30%, and get instant access to the code depot of Oracle tuning scripts.


Expert Remote DBA

BC is America's oldest and largest Remote DBA Oracle support provider.  Get real Remote DBA experts, call
BC Remote DBA today.



Remote DBA Service

Oracle Tuning Book


Advance SQL Tuning Book 

BC Oracle support

Oracle books by Rampant

Oracle monitoring software







BC Remote Oracle Support

Remote DBA

Remote DBA Services

Copyright © 1996 -  2013 by Burleson. All rights reserved.

Oracle® is the registered trademark of Oracle Corporation.