From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org, Pavan Deolasee <pavan(dot)deolasee(at)enterprisedb(dot)com>, Nikhil S <nikhil(dot)sontakke(at)enterprisedb(dot)com>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
Subject: | Re: HOT for PostgreSQL 8.3 |
Date: | 2007-02-09 23:10:12 |
Message-ID: | 200702092310.l19NACM02966@momjian.us |
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Lists: | pgsql-hackers |
Tom Lane wrote:
> > Removing the root tuple will require a VACUUM *FULL*.
>
> That seems unacceptable ... it won't take too long for your table to
> fill up with stubs, and we don't want to return to the bad old days
> when periodic VACUUM FULL was unavoidable.
>
> ISTM we could fix that by extending the index VACUUM interface to
> include two concepts: aside from "remove these TIDs when you find them",
> there could be "replace these TIDs with those TIDs when you find them".
> This would allow pointer-swinging to one of the child tuples, after
> which the old root could be removed. This has got the same atomicity
> problem as for CREATE INDEX, because it's the same thing: you're
> de-HOT-ifying the child. So if you can solve the former, I think you
> can make this work too.
I need clarification here. Is removing dead heap tuple always going to
require an index scan, or was this just for chilling a row (adding an
index)?
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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