On Mon, 2007-09-10 at 20:46 +0100, Heikki Linnakangas wrote: > Bruce Momjian wrote: > > Pavan Deolasee wrote: > >> At the end of pruning: > >> > >> - line pointer of 1 is redirected to 4 > >> - line pointers of 2 and 3 are marked ~LP_USED > >> - the offset of 4 and 5 is unchanged > >>
> > In the quote above, how is Heikki's > > "quick pruning" different from the pruning you are describing? > In "quick pruning", you don't mark the line pointer as not used. > Otherwise someone might reuse the line pointer for another tuple, which > is a problem if you then crash. WAL replay would see an insert to a line > pointer that's already in use (the quick pruning wouldn't be WAL > logged), which would raise an error. That seems like the best way forward to me. It's just a hint that says where the first live tuple is in the chain. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
