| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Florian Pflug <fgp(dot)phlo(dot)org(at)gmail(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(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 18:19:12 |
| Message-ID: | 1189448352.4281.276.camel@ebony.site |
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| Lists: | pgsql-patches |
On Mon, 2007-09-10 at 18:23 +0100, Heikki Linnakangas wrote:
> > If we check a tuple in a chain and the tuple is dead is it possible the
> > pruning operation is cheaper than having to check the tuple again for
> > visibility the next time we see it? If so, we can just always prune
> > when we see a dead tuple in the chain, which I believe was the original
> > design. Pruning becomes an operation similar to marking an index entry
> > as dead. (I assuming pruing does not generate WAL traffic.)
>
> Pruning does generate a WAL record at the moment. Maybe you could do
> some kind of a quick pruning without a WAL record. Like just modify the
> ctid of the oldest dead tuple in the chain, or the redirecting line
> pointer if there is one, to point to the latest live tuple, without
> removing the dead tuples or the line pointers.
Sounds like a great idea.
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
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