Welcome Guest ( Log In | Register )


 
 
 
 
 
 

 
 
Oracle 

Performance Tuning Reference poster
 
Oracle training in Linux 

commands
 
Oracle training Weblogic Book
 
Easy Oracle Jumpstart
 
Oracle training & performance tuning books
 
Burleson Consulting Remote DB Administration
 
 
 
Reply to this topicStart new topic
> Parallel Hint, How is default different?
jerry
post Jul 20 2006, 09:51 AM
Post #1


Member
**

Group: Members
Posts: 14
Joined: 29-September 04
Member No.: 653



Hi,

Can somebody tell me the difference between the following parallel hint formats?

1. select /*+ PARALLEL*/ from emp;
2. select /*+ PARALLEL (t, default) from emp t;

I am seeing different results for each query.

Thanks
Jerry
Go to the top of the page
 
+Quote Post
burleson
post Jul 20 2006, 02:50 PM
Post #2


Advanced Member
***

Group: Members
Posts: 11,714
Joined: 26-January 04
Member No.: 13



Hi Jerry,

default value is two times the number of CPUs in your system

http://www.dba-oracle.com/art_builder_opq_cpu.htm

The danger is setting parallel at the database level with the ALTER TABLE command like this:


Alter table customer parallel degree 35;

The recommended approach for using Parallel query is to add a parallel hint to all SQL statements that perform a full-table scan and would benefit from parallel query.

select /*+ FULL(emp) PARALLEL(emp, 35) */

Here's an OTM discussion of parallel hints:

http://www.oracle.com/technology/oramag/we...bo_pt2_pt1.html


--------------------
Hope this helps. . .

Donald K. Burleson
Oracle Press author
Author of Oracle Tuning: The Definitive Reference
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Lo-Fi Version Time is now: 25th November 2014 - 03:37 PM