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

Parallel Index Building

Figure 7.10 A sample parallel sort.

However, parallel query works best with SMP boxes, which have more than one internal CPU. Also, it is important to configure the system to maximize the I/O bandwidth, either through disk striping or high-speed channels. Because of the parallel sorting feature, it is also a good idea to beef up the memory on the processor.

While sorting is no substitute for using a presorted index, the parallel query manager will service requests far faster than a single process. While the data retrieval will not be significantly faster because all of the retrieval processes are competing for a channel on the same disk, each sort process has its own sort area (as determined by the SORT_AREA_SIZE init.ora parameter), which speeds along the sorting of the result set. In addition to full-table scans and sorting, the parallel query option allows for parallel processes for merge joins and nested loops.
Invoking the parallel query option requires all indexing to be bypassed. And, most importantly, the execution plan for the query should specify a full-table scan. If the output of the explain plan does not indicate a full-table scan, the query can be forced to ignore the index by using query hints.

The number of processors dedicated to servicing an SQL request is ultimately determined by the Oracle query manager, but the programmer can specify the upper limit on the number of simultaneous processes. When using the cost-based optimizer, the PARALLEL hint can be embedded into the SQL to specify the number of processes. For example:

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.