Joshua D. Drake wrote: > Josh Berkus wrote: > > Bruce Momjian wrote: > >> Those who have been with the community from long ago might remember > >> discussion about implementing a undo log. The big advantage of this is > >> that it allows UPDATE to _replace_ rows and limits the amount of cleanup > >> required for UPDATEs. > >> > >> I am hoping that with HOT we will no longer have any need to even > >> consider undo. > >> > > > > We were considering it? > > I don't ever remember us considering it seriously. > > > > > I certainly wasn't. I've enough experience with Oracle and InnoDB to > > see that an undo log is its own set of performane issues. No thanks. > > > > It certainly does.
We never actually considred undo, but high UPDATE activity was one of the areas we historically handled poorly compared to undo systems, and undo would have been one way to improve that area. I think with HOT we have improved high UPDATE activity enough that the undo benefits are no longer attractive (and of course the undo disadvantages were never attractive). -- Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us EnterpriseDB http://postgres.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
