Re: Update Statements and Exadata

From: David Fitzjarrell <oratune_at_yahoo.com>
Date: Sun, 9 Dec 2012 02:09:53 -0800 (PST)
Message-ID: <1355047793.113.YahooMailNeo_at_web121603.mail.ne1.yahoo.com>

Basically serial processing does not perform direct path reads where parallel does.  Since one criteria for smart scans is utilizing direct path reads you don't get them with serial processing.  You could, if you really wanted to, set _serial_direct_path to true (it's false by default) but that could introduce performance problems and slowdowns.
 

David Fitzjarrell
 

---

 From: coskan gundogar <coskan_at_gmail.com> To: Oracle Discussion List <oracle-l_at_freelists.org> Sent: Sunday, December 9, 2012 2:43 AM
Subject: Update Statements and Exadata  

All,
Can anybody let me know the difference for the internal mechanism on parallel update and serial update

When I run serial update Oracle can't offload the statement (I assume this is due to dealing with undo)

If I run the statement parallel (no partitioning) it can offload the scanning part.

I would really appreciate if somebody can walk me through the difference between serial and parallel and why serial is no go.

Regards

-- 
-- 
Coskan GUNDOGAR

Oracle DBA

Email: coskan_at_gmail.com
Blog: http://coskan.wordpress.com
Twitter: http://www.twitter.com/coskan
Linkedin: http://uk.linkedin.com/in/coskan


--
http://www.freelists.org/webpage/oracle-l

--
http://www.freelists.org/webpage/oracle-l

Received on Sun Dec 09 2012 - 11:09:53 CET