From oracle-l-bounce@freelists.org Fri Jun 25 14:31:48 2004 Return-Path: Received: from air189.startdedicated.com (root@localhost) by orafaq.com (8.11.6/8.11.6) with ESMTP id i5PJVWr08207 for ; Fri, 25 Jun 2004 14:31:43 -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 i5PJVM608178 for ; Fri, 25 Jun 2004 14:31:32 -0500 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id AEEF572CB40; Fri, 25 Jun 2004 14:14:33 -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 22596-25; Fri, 25 Jun 2004 14:14:33 -0500 (EST) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id E01CB72CB51; Fri, 25 Jun 2004 14:14:32 -0500 (EST) Received: with ECARTIS (v1.0.0; list oracle-l); Fri, 25 Jun 2004 14:13:07 -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 C190672C393 for ; Fri, 25 Jun 2004 14:13:06 -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 20536-91 for ; Fri, 25 Jun 2004 14:13:06 -0500 (EST) Received: from ahmler4.mail.eds.com (ahmler4.mail.eds.com [192.85.154.77]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 4094072C11F for ; Fri, 25 Jun 2004 14:13:06 -0500 (EST) Received: from ahmlir4.mail.eds.com (ahmlir4-2.mail.eds.com [192.85.154.134]) by ahmler4.mail.eds.com (8.12.10/8.12.10) with ESMTP id i5PJZ0wF002245 for ; Fri, 25 Jun 2004 15:35:01 -0400 Received: from ahmlir4.mail.eds.com (localhost [127.0.0.1]) by ahmlir4.mail.eds.com (8.12.10/8.12.10) with ESMTP id i5PJY5Zm010289 for ; Fri, 25 Jun 2004 15:34:05 -0400 Received: from USAHM102.amer.corp.eds.com (usahm102.exmi01.exch.eds.com [207.37.138.190]) by ahmlir4.mail.eds.com (8.12.10/8.12.10) with ESMTP id i5PJY5d7010283 for ; Fri, 25 Jun 2004 15:34:05 -0400 Received: by usahm102.exmi01.exch.eds.com with Internet Mail Service (5.5.2657.72) id ; Fri, 25 Jun 2004 15:33:41 -0400 Message-ID: <564DE4477544D411AD2C00508BDF0B6A1CE0ABB2@usahm018.exmi01.exch.eds.com> From: "Powell, Mark D" To: "'oracle-l@freelists.org'" Subject: RE: Script to overcome ORA-54 during DDL Date: Fri, 25 Jun 2004 15:33:38 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Content-type: text/plain; charset=iso-8859-1 X-Virus-Scanned: by amavisd-new at freelists.org Content-Transfer-Encoding: 8bit X-archive-position: 3724 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-To: oracle-l-bounce@freelists.org X-original-sender: mark.powell@eds.com Precedence: normal Reply-To: oracle-l@freelists.org X-list: oracle-l X-Virus-Scanned: by amavisd-new at freelists.org Mark, UL locks once granted are held until released via dbms_lock.release or the session terminates and therefore would cover multiple commits actions if that is what the holding process does. UL locks are also a relatively expensive resource according to the Oracle documentation and requiring every session to take a share level UL lock on a table and then release it for OLTP type work would be a lot of overhead relative to the work being done. IMHO -- Mark D Powell -- -----Original Message----- From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org]On Behalf Of Bobak, Mark Sent: Friday, June 25, 2004 3:21 PM To: oracle-l@freelists.org Subject: RE: Script to overcome ORA-54 during DDL Seems to me, if you have control over the code base, and you know these = types of things will be necessary, you could implement something via DBMS_LOCK. Any time a DML executes, it could first take a user defined (UL) enqueue in shared mode. It does it's DML, commit/rollback, and the UL is = released atomically w/ the DML. Now, you come along and need to do mainenance. So, you exec dbms_lock on the same UL enqueue, but in exclusive mode, and if any DML is executing, you'll queue up and wait on that enqueue. When all pending DML commits/rolls back, you'll get your exclusive UL lock, and you can do the DDL. While this is going on, all DML will queue up, till the exclusive lock clears. When you're done w/ the DDL, release the exclusive lock, all DML continues where it left off. Hmm...just thought of something. DDL implies commit before and after the change that it's making. Would that first commit release the lock on the UL enqueue? Hmmm, maybe that's not such a good idea. I'll have to test it out..... -Mark -----Original Message----- From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org]On Behalf Of Jeremiah Wilton Sent: Friday, June 25, 2004 2:56 PM To: oracle-l@freelists.org Subject: Script to overcome ORA-54 during DDL Sometimes when trying to perform DDL on really hot objects (heavy read/DML), I get: ORA-00054: resource busy and acquire with NOWAIT specified. I guess this is because you need to obtain a library cache lock in order to change the object definition. Since there is no enqueue mechanism for this resource, you can't just 'lock table ... in exclusive mode;' All that gives you is a DML lock. One way to avoid this is to write a PL/SQL routine that uses DBMS_SQL and spins trying to run the DDL, stopping only when it succeeds. This seems to work most of the time. Does anyone have a script for doing the above that they would like to share? Please don't tell me to just use dbms_redefinition. That is unnecessarily complex when the above technique can be used instead. Thanks -- Jeremiah Wilton http://www.speakeasy.net/~jwilton ---------------------------------------------------------------- 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 -----------------------------------------------------------------