Re: MVCC, undo log, and HOT

Josh Berkus wrote:
> Bruce,
> 
> > 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).
> > 
> 
> If you're asking if we should remove the TODO (is there one?) and 
> replace it with a FAQ item called "Why PostgreSQL doesn't have an UNDO 
> LOG", then my vote is "yes".

No, it never got close to being a TODO item.  It was more a limitation
we had that is now fixed.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://postgres.enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +