From oracle-l-bounce@freelists.org Wed Mar 31 13:56:36 2004 Return-Path: Received: from air189.startdedicated.com (root@localhost) by orafaq.com (8.11.6/8.11.6) with ESMTP id i2VJuYP09032 for ; Wed, 31 Mar 2004 13:56:34 -0600 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 i2VJuXo09027 for ; Wed, 31 Mar 2004 13:56:34 -0600 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 2C794635DEC; Wed, 31 Mar 2004 14:52:24 -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 12018-34; Wed, 31 Mar 2004 14:52:23 -0500 (EST) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id C1251635CCE; Wed, 31 Mar 2004 14:51:43 -0500 (EST) Received: with ECARTIS (v1.0.0; list oracle-l); Wed, 31 Mar 2004 14:50:27 -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 0C2FE635976 for ; Wed, 31 Mar 2004 14:50:26 -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 11213-78 for ; Wed, 31 Mar 2004 14:50:25 -0500 (EST) Received: from webhost-2.webgnostics.com (webhost-2.webgnostics.com [65.162.17.13]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 04C7A635853 for ; Wed, 31 Mar 2004 14:50:15 -0500 (EST) Received: from dmc-it.com (localhost.localdomain [127.0.0.1]) (authenticated (0 bits)) by webhost-2.webgnostics.com (8.11.6/8.11.6) with ESMTP id i2VJvcU03663 for ; Wed, 31 Mar 2004 14:57:38 -0500 Received: from targai.nationwide.com ([155.188.255.4]) (proxying for 192.168.38.130) (SquirrelMail authenticated user jtesta@dmc-it.com) by www.dmc-it.com with HTTP; Wed, 31 Mar 2004 14:57:38 -0500 (EST) Message-ID: <62121.155.188.255.4.1080763058.squirrel@www.dmc-it.com> Date: Wed, 31 Mar 2004 14:57:38 -0500 (EST) Subject: Re: RE: shared pool latch From: To: In-Reply-To: <20040331193813.GKCG18400.lakemtao06.cox.net@smtp.central.cox.net> References: <20040331193813.GKCG18400.lakemtao06.cox.net@smtp.central.cox.net> X-Priority: 3 Importance: Normal X-Mailer: SquirrelMail (version 1.2.11) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 X-Virus-Scanned: by amavisd-new at freelists.org X-archive-position: 2232 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-To: oracle-l-bounce@freelists.org X-original-sender: jtesta@dmc-it.com Precedence: normal Reply-To: oracle-l@freelists.org X-list: oracle-l X-Virus-Scanned: by amavisd-new at freelists.org when they were born(or hatched)? it just had to be said. joe original message below what is the difference between a child cursor and a parent cursor? From: Riyaj Shamsudeen Date: 2004/03/31 Wed PM 12:15:42 EST To: oracle-l@freelists.org Subject: RE: shared pool latch Let me try to keep this alive.. Responses in line.. HTH Thanks Riyaj "Re-yas" Shamsudeen Certified Oracle DBA -----Original Message----- From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of Sultan Syed Sent: Wednesday, March 31, 2004 4:21 AM To: oracle freelists.org Subject: shared pool latch Hi guys The following questions are confusing me,please could someone give explanation on the below 1)Is librarycache latch held during the whole process of parse,execute and fetch phases , or it is held upto the time searching for the object in hash table and release. Library cache latch is held while searching for a parent cursor and subsequent child cursor with similar attributes with parent cursor pinned. Also library cache latch is held when creating a new library cache object if the child cursor is not_found or found_but_not_shareable. Since, parent cursor is pinned while searching for a child cursor, I am not sure whether the search for child cursor needs to hold on to the library cache latch or not. But if a new parent cursor is to be created then the library cache latch must be held. Execute and Fetch uses library cache pin and library cache locks to maintain the objects from undergoing concurrent modification. 2)session_cached_cursor caches the child cursor or parent cursors also. As far as I know, session_cached_cursor is searched for pinned child cursor. I don't know whether the parent is also kept in the session cached cursor or not. 3)While doing hard parse which latch is acquired ,shared pool or library cache latch or both, if it is both which latch will be acquired first? library cache latch is already held while requesting for shared pool latch. Shared pool latch is acquired to request/release space from the shared pool free memory area and released immediately after that. Request for library cache latch can never be made while holding the shared pool latch (at least up to 9i) as latch level semantics will prevent that ( as shared pool latch gets are always in willing-to-wait mode). Thanks in advance Syed The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. If the reader of this message is not the intended recipient, you are hereby notified that your access is unauthorized, and any review, dissemination, distribution or copying of this message including any attachments is strictly prohibited. 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