"Florian G. Pflug" <fgp@xxxxxxxx> writes: > I'm looking for a way to recover deleted or old versions of > accidentally updated rows from a postgres 7.4 database. I've > verified that the relevant tables haven't been vacuumed since > the accident took place. > I was thinking that it might work to patch the clog so that > the offending transactions look like they have never been > comitted? Would that work? How could I patch the clog? By this point the lost rows are no doubt marked HEAP_XMAX_COMMITTED, which means that hacking the clog entries wouldn't accomplish anything by itself --- you'd have to go and unset those hint bits, too. Given that, you might as well not bother with patching clog; it wouldn't be any more trouble to unset HEAP_XMAX_COMMITTED and set HEAP_XMAX_INVALID in each tuple you needed to resurrect. You'd need a custom tool to do either though :-( regards, tom lane
