Think of something like a temporary load table. If you have a large load process that is generating thousands of extents the clearing of the temp table before the loads will kill you. During the truncate or delete SMON clears all the extent info out of SYS.UET$ and adds them to SYS.FET$. With very large numbers of extents this time is considerable. We once had a temporary tablespace that was created as permanent. When we went to drop that tablespace (8GB) and change it to temporary it took us about 18 hours. The whole system hung up while SMON was working.
For a load table, like mentioned in my first line, you would want to create it as large as you calculate the load to be and then make it one huge extent. Truncating before the load will be significantly faster. Rodd Holman -----Original Message----- To: Multiple recipients of list ORACLE-L Sent: 10/2/01 4:15 PM Why is that? And would that only count for an object in a dictionary managed tablespace? Would the time/speed it takes for drops and truncates really matter as far as performance is concerned? What I mean is who would set storage specs for objects with the speed it takes for truncates and drops of that object in mind? It would seem to me that if an object is getting dropped or truncated that often that speed should be an issue, there are bigger problems at hand. Guru's correct me if I'm wrong please. Later, Ivan -----Original Message----- <mailto:[EMAIL PROTECTED]> ] Sent: Tuesday, October 02, 2001 3:56 PM To: Multiple recipients of list ORACLE-L Any DDL like drop table and truncate table definately take longer with 10,000 extents than 1 extent. Try it. There was a test result 1 year back by a list member on that. Regards MOHAMMAD RAFIQ Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> Date: Tue, 02 Oct 2001 07:55:28 -0800 That is completely a myth. There is no notable performance different with a table with 10,000 extents and one with 1. The only problem is when it comes to the bitmaps when dealing with LMT and cluster when dealing with dictionary managed. When you query the extent views, or do space management type processes. "Do not criticize someone until you walked a mile in their shoes, that way when you criticize them, you are a mile a way and have their shoes." Christopher R. Spence Oracle DBA Phone: (978) 322-5744 Fax: (707) 885-2275 Fuelspot 73 Princeton Street North, Chelmsford 01863 -----Original Message----- Sent: Monday, October 01, 2001 7:15 PM To: Multiple recipients of list ORACLE-L May be it is good practice to keep number of extents to be less than 50, no matter what the size of extent. -----Original Message----- Sent: Monday, October 01, 2001 3:35 PM To: Multiple recipients of list ORACLE-L Hello, I'll do an reorganization of a database (about 140 gigs). Some people say that it'd be good to use 128K, 4M and 128M extents. I saw somewhere it'd be 160K, 4M and 160M. Which size do you advice me ? I have also many small indexes (less than 16K). 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You may also send the HELP command for other information (like subscribing). _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp <http://explorer.msn.com/intl.asp> -- Please see the official ORACLE-L FAQ: http://www.orafaq.com <http://www.orafaq.com> -- Author: Mohammad Rafiq INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). 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