From oracle-l-bounce@freelists.org Fri Apr 30 21:54:55 2004 Return-Path: Received: from air189.startdedicated.com (root@localhost) by orafaq.com (8.11.6/8.11.6) with ESMTP id i412sev13200 for ; Fri, 30 Apr 2004 21:54:50 -0500 X-ClientAddr: 206.53.239.180 Received: from turing.freelists.org (freelists-180.iquest.net [206.53.239.180]) by air189.startdedicated.com (8.11.6/8.11.6) with ESMTP id i412sU613193 for ; Fri, 30 Apr 2004 21:54:40 -0500 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id F1A8972CB12; Fri, 30 Apr 2004 21:46:05 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 06641-06; Fri, 30 Apr 2004 21:46:05 -0500 (EST) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 46ED772CAD6; Fri, 30 Apr 2004 21:46:05 -0500 (EST) Received: with ECARTIS (v1.0.0; list oracle-l); Fri, 30 Apr 2004 21:44:51 -0500 (EST) X-Original-To: oracle-l@freelists.org Delivered-To: oracle-l@freelists.org Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 19E4A72CA73 for ; Fri, 30 Apr 2004 21:44:51 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 05033-63 for ; Fri, 30 Apr 2004 21:44:50 -0500 (EST) Received: from maillnx-us312.fmr.com (maillnx-us312.fmr.com [192.223.178.27]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 9958772CA47 for ; Fri, 30 Apr 2004 21:44:50 -0500 (EST) Received: from virmmk111nts.fmr.com (virmmk111nts.fmr.com [172.25.106.96]) by maillnx-us312.fmr.com (Switch-3.1.2/Switch-3.1.0) with SMTP id i412vtpg016840 for ; Fri, 30 Apr 2004 22:57:55 -0400 Received: from MSGBOSCLF2WIN.fmr.com ([10.46.17.175]) by MSGMROIM01WIN.DMN1.FMR.COM with Microsoft SMTPSVC(5.0.2195.6713); Fri, 30 Apr 2004 22:57:55 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.0.6521.0 content-class: urn:content-classes:message Subject: RE: TC Enqueue waits MIME-Version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Date: Fri, 30 Apr 2004 22:57:55 -0400 Message-ID: <42BBD772AC30EA428B057864E203C9991158FB@MSGBOSCLF2WIN.DMN1.FMR.COM> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: TC Enqueue waits Thread-Index: AcQu5FruaLlkfPxUSl6jE+e4dkUoZgAPWPzQ From: "Khedr, Waleed" To: X-OriginalArrivalTime: 01 May 2004 02:57:55.0410 (UTC) FILETIME=[19F80B20:01C42F28] X-Virus-Scanned: by amavisd-new at freelists.org X-archive-position: 4148 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-To: oracle-l-bounce@freelists.org X-original-sender: Waleed.Khedr@FMR.COM Precedence: normal Reply-To: oracle-l@freelists.org X-list: oracle-l X-Virus-Scanned: by amavisd-new at freelists.org I can't say that I'm 100% sure about the details, but I can say I was = able to observe this behavior many times in environments that mix oltp = (serial transactions) and Data Warehouses (reports that use PQO). Also think about the fact, that direct reads go directly to files/TS = where there might be a chance of having some dirty buffers that belong = to that segment & Tablespace that could really affect the = uniqueness/integrity of data being extracted by direct reads. I'm sure many of the enqueue/X$/v$ experts on this list can correct me = or add more details. Regards, Waleed -----Original Message----- From: Diego Cutrone [mailto:diegocutrone@yahoo.com.ar] Sent: Friday, April 30, 2004 6:54 PM To: oracle-l@freelists.org Subject: Re: TC Enqueue waits Thank you Waleed Let me confirm what I understood. So you're telling me that when an object needs to be accessed by using = PQO, the session that required this access will (possible) have to wait on a TC enqueue waiting for the dirty buffers to get into disk. did I = get it correctly? I thought the session used to waiting on the cross instance call (CI) enqueue while an object checkpoint was taking place (before a direct = read takes place).... Please, let me know your thoughts. Thanks! Diego. ----- Original Message -----=20 From: "Khedr, Waleed" To: Sent: Friday, April 30, 2004 10:50 AM Subject: RE: TC Enqueue waits > PQ slaves uses direct reads bypassing the SGA to read the segment = blocks =3D > which requires waiting to flush all committed > changes in the SGA (dirty buffers) of that object to make sure the PQ = =3D > slaves > will access the most recent version of that object. > > Regards, > > Waleed > > -----Original Message----- > From: Diego Cutrone [mailto:diegocutrone@yahoo.com.ar] > Sent: Friday, April 30, 2004 4:25 PM > To: Oracle List > Subject: TC Enqueue waits > > > Hi List. > I have detected high enqueue waits in one instance. > After quering x$ksqst I realized most of them were TX and TC enqueues. > > I'm on the TX enqueues by tracing some sessions. But I have never = heard =3D > of TC enqueues > I have read that TC enqueue stands for "Thread Checkpoint = enqueue".=3D20 > > Anybody knows what are they used for? what kind of resources they =3D > protect? > > And I have another quick question: > > I'm also seeing Parallel query events like: > > PX Deq: Execution Msg > PX Idle Wait > PX qref latch=3D20 > PX Deq: Execute Reply=3D20 > PX Deq: Table Q Normal=3D20 > PX Deq: Parse Reply=3D20 > > Does anybody know where I can get a description for them?=3D20 > I'd like to know which ones can be ignored and which ones can't. > > Thank you very much > Regards > Diego > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@freelists.org > put 'unsubscribe' in the subject line. > -- > Archives are at http://www.freelists.org/archives/oracle-l/ > FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@freelists.org > put 'unsubscribe' in the subject line. > -- > Archives are at http://www.freelists.org/archives/oracle-l/ > FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- > ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@freelists.org put 'unsubscribe' in the subject line. -- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@freelists.org put 'unsubscribe' in the subject line. -- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------