| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Open issues for HOT patch |
| Date: | 2007-09-18 03:38:41 |
| Message-ID: | 25129.1190086721@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
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.
regards, tom lane
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