Re: Open issues for HOT patch

Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Tom Lane wrote:
> >> The problem is you can't prune anymore once you have existing pin on the
> >> target page. I'd really like to get around that, but so far it seems
> >> unacceptably fragile --- the executor really doesn't expect tuples to
> >> get moved around underneath it.
>
> > I thought you could do the pruning before you pin the page only in
> > update/insert cases.
>
> But then what happens when you want to update a second tuple on the same
> page? None of our existing plan types release and reacquire pin if they
> don't have to, and I really doubt that we want to give up that
> optimization.

You will prune when you lock the page and at that point unless you got
enough room for both tuples I doubt trying just before the second tuple
is going to help.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com

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