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
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• Original Message -----
  > Date: Sat, 10 Feb 2007 09:44:46 -0800 (PST)
  > From: Sai Selvaganesan <ssaisundar_at_sbcglobal.net>
  > 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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