I get the idea but I can't change the structure of the database by adding anything. I have a database from which I have to retrieve some history data for recovery purposes. > Date: Fri, 27 Aug 2010 13:11:47 -0400 > From: webmaster@dhs-club.com > To: lukasz.brodziak@hotmail.com; pgsql-admin@postgresql.org > Subject: Re: [ADMIN] Tuple changes from relfilenodes > > >> Are you looking for statistics or the actual prior versions of > >> rows? > > > > I'm looking for actual versions of row data. What I want to > > achieve as a final result is a kind of data change history. > > We just use ON DELETE rules on the tables where we want to maintain a history. In most cases, we just copy the old record to the archive table which has an additional timestamp column with a default of NOW() to indicate the date of archival. In one case, where the table schema is large, changes are "frequent" and the changes are often minimal, we only archive a small subset of data based on what is changing. If the changes affect columns outside of the small subset, then we archive the whole record. > > Bill MacArthur >
