Re: oracle-l Digest V4 #42


It doesn't matter if the HV Enqueue is the highest wait time
if it is a small fraction of the total time - and you didn't answer
the question about that.

I would guess that a lot of the enqueue time appears because
this is a global enqueue that has to be negotiated across nodes.
So reducing the degree of parallelism may help; reducing the
number of nodes used in the creation may help.

Is the tablespace using ASSM - that might make a difference
because there is a difference in space allocation between
freelist management and ASSM that might be relevant.


Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
----- Original Message ----- 
Date: Sat, 10 Feb 2007 09:44:46 -0800 (PST)
From: Sai Selvaganesan <ssaisundar@xxxxxxxxxxxxx>
Subject: Re: HV enqueue

thx for the reply
the number of slaves it very high(32) for a table creation (table size at the end of the creation is 20GB) 
 will reducing this amount of parallelsim benefit.
regarding the question about how big a problem this HV contention is, it is the biggest wait event during CTAS. would you recommend disabling the HWM through underscore parameter or would you see if reducing the parallelsim along with the number of nodes this can run help this or increase the extent size. now CTAS runs on all nodes(it is a 10 node rac) with this hig a parallelism (i personally feel this is a baad way to do but i would love your recommendation) 
 again
 thx a lot for your help
 sai




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