Kevin Grittner wrote: > *ukasz Brodziak<lukasz.brodziak@xxxxxxxxxxx> wrote: > > From: Kevin.Grittner@xxxxxxxxxxxx > > >> 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. > > Well, unless you are suppressing the vacuum behavior which normally > occurs, your history won't go back very far; and if you do suppress > vacuums, performance will begin to fall of fairly quickly. > > Tuples representing old versions of rows may be eliminated as soon > as there is no transaction which would still be able to see them. Well, single-page vacuums are even more likely to remove old data, and you can't turn that off. I am working on am MVCC talk for PG/West that will show how agressive those single-page (HOT and non-HOT) vacuums are. -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
