| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Hannu Krosing <hannu(at)skype(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Csaba Nagy <nagy(at)ecircle-ag(dot)com>, Mark Woodward <pgsql(at)mohawksoft(dot)com>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Christopher Browne <cbbrowne(at)acm(dot)org>, postgres hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: vacuum, performance, and MVCC |
| Date: | 2006-06-26 05:49:28 |
| Message-ID: | 20060626054927.GA6341@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Jan Wieck wrote:
> On 6/25/2006 10:12 PM, Bruce Momjian wrote:
> >When you are using the update chaining, you can't mark that index row as
> >dead because it actually points to more than one row on the page, some
> >are non-visible, some are visible.
>
> Back up the truck ... you mean in the current code base we have heap
> tuples that are visible in index scans because of heap tuple chaining
> but without index tuples pointing directly at them?
I don't know where this idea came from, but it's not true. All heap
tuples, dead or otherwise, have index entries. Unless the idea is to
extend update chaining to mean something different from the current
meaning.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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