Path: newssvr20.news.prodigy.com!newsmst01.news.prodigy.com!prodigy.com!news.glorb.com!newsfeed.stueberl.de!newsr1.ipcore.viaginterkom.de!news-peer1!btnet-feed5!btnet!news.btopenworld.com!not-for-mail From: "Jonathan Lewis" Newsgroups: comp.databases.oracle.server Subject: Re: RMAN internal`s mechanism Date: Wed, 3 Mar 2004 10:55:11 +0000 (UTC) Organization: BT Openworld Lines: 50 Message-ID: References: <74c5bf11.0403030230.1464f170@posting.google.com> NNTP-Posting-Host: host81-133-96-153.in-addr.btopenworld.com X-Trace: sparta.btinternet.com 1078311311 5359 81.133.96.153 (3 Mar 2004 10:55:11 GMT) X-Complaints-To: news-complaints@lists.btinternet.com NNTP-Posting-Date: Wed, 3 Mar 2004 10:55:11 +0000 (UTC) X-Newsreader: Microsoft Outlook Express 6.00.2800.1158 X-MSMail-Priority: Normal X-Priority: 3 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Xref: newssvr20.news.prodigy.com comp.databases.oracle.server:256190 Notes in-line -- Regards Jonathan Lewis http://www.jlcomp.demon.co.uk The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html March 2004 Hotsos Symposium - The Burden of Proof Dynamic Sampling - an investigation March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial April 2004 Iceland June 2004 UK - Optimising Oracle Seminar "Ofer Razon" wrote in message news:74c5bf11.0403030230.1464f170@posting.google.com... > Hi all. > > As far as I know, RMAN is capable to backup only the blocks that > changed since it`s last backup. > I`m really interested in the mechanism used by RMAN to detect these > blocks when it runs. > Does anyone here know how is it implemented? > Every block has a last change number - which is the SCN at the last change plus a counter that goes from 1 to 254. rman knows when the SCN when it last did a backup, reads each block, and checks the last change number. > My goal is to use the same mechanism to find which blocks were changed > since the last check. > Possible - so long as you knew the SCN when rman started (or perhaps when it started each file, or tablespace - that's a little detail that I'm not so sure on; the file would be the obvious choice). The last change SCN is in a fixed location in the block, so you could write some 3GL code to scan each file and pick it out from each block. I am curious to know why you want to do this. > Ofer.