| From: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
|---|---|
| To: | "Bruce Momjian" <bruce(at)momjian(dot)us> |
| Cc: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Florian Pflug" <fgp(dot)phlo(dot)org(at)gmail(dot)com>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: HOT patch - version 15 |
| Date: | 2007-09-10 19:52:00 |
| Message-ID: | 2e78013d0709101252p42b79697r3572e6a5f7bb96ea@mail.gmail.com |
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| Lists: | pgsql-patches |
On 9/11/07, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
>
>
> Right. My point is that pruning only modifies item pointers. It does
> not change the actual heap tuples. In the quote above, how is Heikki's
> "quick pruning" different from the pruning you are describing?
>
>
>
I think the only difference is that the quick pruning does not mark
intermediate tuples ~LP_USED and hence we may avoid WAL logging.
Btw, I am not too enthusiastic about quick pruning because it leaves
behind dead heap-only tuples which are not reachable from any root
heap tuples. Not that we can't handle them, but I am worried about
making such changes right now unless we are sure about the benefits.
We can always tune and tweak in 8.4
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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