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Re: HOT patch - version 15

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: HOT patch - version 15
Date: 2007-09-05 22:07:21
Message-ID: 200709052207.l85M7L306505@momjian.us (view raw or flat)
Thread:
Lists: pgsql-patches
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > I am thinking we are best just doing the index chain we already have to
> > read.   
> 
> > If you are modifying the table (like with UPDATE) it makes sense to be
> > more aggressive and do the whole page because you know there are
> > probably other table modifications, but for an index lookup there isn't
> > any knowledge of whether the table is being modified so looking at more
> > than we need seems like overkill.
> 
> Uh, why would any of this code at all execute during a pure lookup?

No idea.  It seems an index lookup tries to prune a heap chain, and he
was asking if it should look at other chains on the page;  I said not. 
Whether the index lookup should prune the heap chain is another issue.

-- 
  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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