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Re: One-time plans

From: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: One-time plans
Date: 2007-04-02 17:52:47
Message-ID: 1175536367.4386.1102.camel@silverbirch.site (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, 2007-04-02 at 12:20 -0400, Tom Lane wrote:
> "Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
> > ISTM we've just invented the concept of one-time plans to allow CREATE
> > INDEX to work effectively with HOT.
> 
> > I'd like to extend that thought back over towards constraint exclusion.
> > Currently we don't allow STABLE functions to be used for constraint
> > exclusion because that mean plans were valid only if they are
> > immediately executed.
> 
> > It seems like a very small act to force the plan to be one-time only
> > when we have successfully used a STABLE function to exclude a table.
> 
> No.  STABLE functions are not stable enough for that --- you'd have to
> assume they are unchanging across the whole transaction.

Yep. I was mainly thinking about single statement transactions, which
are the norm for decision support.

-- 
  Simon Riggs             
  EnterpriseDB   http://www.enterprisedb.com



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