Re: HOT for PostgreSQL 8.3

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@momjian.us>          http://momjian.us EnterpriseDB
http://www.enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +