Return-Path: Delivered-To: 2-oracle-l@orafaq.com Received: (qmail 15551 invoked from network); 12 Sep 2007 13:36:47 -0500 Received: from freelists-180.iquest.net (HELO turing.freelists.org) (206.53.239.180) by 69.64.49.119 with SMTP; 12 Sep 2007 13:36:46 -0500 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 1FE717417F9; Wed, 12 Sep 2007 13:58:04 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 09332-07; Wed, 12 Sep 2007 13:58:03 -0400 (EDT) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 694F274117F; Wed, 12 Sep 2007 13:58:03 -0400 (EDT) Received: with ECARTIS (v1.0.0; list oracle-l); Wed, 12 Sep 2007 13:13:32 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 29AA0741F95 for ; Wed, 12 Sep 2007 13:13:32 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 30723-03 for ; Wed, 12 Sep 2007 13:13:32 -0400 (EDT) Received: from web806.biz.mail.mud.yahoo.com (web806.biz.mail.mud.yahoo.com [209.191.90.79]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with SMTP id 55F54741FF3 for ; Wed, 12 Sep 2007 13:13:14 -0400 (EDT) Received: (qmail 72001 invoked by uid 60001); 12 Sep 2007 17:51:50 -0000 X-YMail-OSG: QPY7U6QVM1mD3lpB_fkIUscl9fkltjvXXpWn21e5HjfBeb4zZCUosM0wsBvKvCyirOFaKhJuDIy1EXwZxqK_a8HgR.wTYc2eTpyTBHKwgvAut3yw0S8- Received: from [63.146.24.10] by web806.biz.mail.mud.yahoo.com via HTTP; Wed, 12 Sep 2007 10:51:50 PDT Date: Wed, 12 Sep 2007 10:51:50 -0700 (PDT) From: David Aldridge Subject: RE: Causes of CF (Control file) Enqueues on Index Creation? To: T.Koppelaars@centraal.boekhuis.nl, Oracle List In-Reply-To: <1247DEDC2684644C93827EB6FDF47F9A0320A8C7@SRVEVS1.boekhuis.nl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1545666821-1189619510=:70389" Message-ID: <583540.70389.qm@web806.biz.mail.mud.yahoo.com> X-archive-position: 1480 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-to: oracle-l-bounce@freelists.org X-original-sender: david@david-aldridge.com Precedence: normal Reply-to: david@david-aldridge.com List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: oracle-l X-List-ID: oracle-l List-subscribe: List-owner: List-post: List-archive: X-list: oracle-l X-Virus-Scanned: Debian amavisd-new at localhost.localdomain --0-1545666821-1189619510=:70389 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit If the load were modified to be direct path, and I've no idea why it isn't already to be honest, then my intuition tells me that would remove the possibility of delayed block cleanout occuring ... does that sound correct? I can't think why the blocks would need to be cleaned following direct path insert. "Koppelaars, Toon" wrote: v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} If delayed block cleanout causes writes to the controlfile, then this might be your problem. When the index is created then the blocks are reread from disk and at that moment are cleaned out and all the parallel slaves are fighting for the CF enqueue. --------------------------------- From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of David Aldridge Sent: woensdag 12 september 2007 14:32 To: Oracle List Subject: Causes of CF (Control file) Enqueues on Index Creation? We recently noticed, through Quest Performance Analysis, that a particular index creation statement on a newly populated table occasionally suffers from enqueue waits that extend the creation time from a few minutes to over an hour. We used statspack to investigate further and found that at the time of index creation we get a spike in CF enqueue waits. I have read Anjo Kolk's whitepaper "Description of Oracle7 Wait Events and Enqueues" http://www.akadia.com/download/documents/session_wait_events.pdf in which he identifies an imposing list of situations in which the CF enqueue is used. The index is a locally partitioned single column uncompressed b-tree built in parallel degree 8 against a range partitioned heap table with 8 partitions. The table has just been loaded when this index is created and it's the first to be created post-load. Other subsequently-built indexes do not appear to have suffered from this problem. the index creation takes place in a new session that starts immediately after a previous session has populated the table, commited and gracefully exited. The issue occurs intermittently, not on every occasion that the table is loaded. I don't have access to the statspack data we extracted at the moment ... I'll post it as soon as I do. Does anyone have any quick thoughts about the relationship between creating an index and a control file lock? I'm really pushing the limits of my internals knowledge here -- OK, actually I have gone past it :( --0-1545666821-1189619510=:70389 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit If the load were modified to be direct path, and I've no idea why it isn't already to be honest, then my intuition tells me that would remove the possibility of delayed block cleanout occuring ... does that sound correct? I can't think why the blocks would need to be cleaned following direct path insert.

"Koppelaars, Toon" <T.Koppelaars@centraal.boekhuis.nl> wrote:
If delayed block cleanout causes writes to the controlfile, then this might be your problem.
 
When the index is created then the blocks are reread from disk and at that moment are cleaned out and all the parallel slaves are fighting for the CF enqueue.
 
From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of David Aldridge
Sent: woensdag 12 september 2007 14:32
To: Oracle List
Subject: Causes of CF (Control file) Enqueues on Index Creation?
 
We recently noticed, through Quest Performance Analysis, that a particular index creation statement on a newly populated table occasionally suffers from enqueue waits that extend the creation time from a few minutes to over an hour.
 
We used statspack to investigate further and found that at the time of index creation we get a spike in CF enqueue waits.
 
I have read Anjo Kolk's whitepaper "Description of Oracle7 Wait Events and Enqueues" http://www.akadia.com/download/documents/session_wait_events.pdf in which he identifies an imposing list of situations in which the CF enqueue is used.
 
The index is a locally partitioned single column uncompressed b-tree built in parallel degree 8 against a range partitioned heap table with 8 partitions. The table has just been loaded when this index is created and it's the first to be created post-load. Other subsequently-built indexes do not appear to have suffered from this problem. the index creation takes place in a new session that starts immediately after a previous session has populated the table, commited and gracefully exited. The issue occurs intermittently, not on every occasion that the table is loaded.
 
I don't have access to the statspack data we extracted at the moment ... I'll post it as soon as I do.
 
Does anyone have any quick thoughts about the relationship between creating an index and a control file lock? I'm really pushing the limits of my internals knowledge here -- OK, actually I have gone past it :(

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