| 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 |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| 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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