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Re: WIP: generalized index constraints

From: David Fetter <david(at)fetter(dot)org>
To: Brendan Jurd <direvus(at)gmail(dot)com>
Cc: Jeff Davis <pgsql(at)j-davis(dot)com>,Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: WIP: generalized index constraints
Date: 2009-08-22 19:14:37
Message-ID: 20090822191436.GE6792@fetter.org (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Aug 21, 2009 at 12:23:15PM +1000, Brendan Jurd wrote:
> 2009/8/21 Jeff Davis <pgsql(at)j-davis(dot)com>:
> > If they include indexes and not constraints, I think we should
> > follow the same policy as unique constraints, and create the index
> > and the constraint.
> >
> > The behavior seems a little strange to me, but that's the current
> > behavior for unique indexes.
> 
> This may be an opportunity to fix it.
> 
> The current behaviour seems to be predicated on the unique
> constraint being an integral part of the index itself.  While this
> might be true from a system catalog point of view
> (pg_index.indisunique), if a user says that they want to copy a
> table's structure INCLUDING INDEXES EXCLUDING CONSTRAINTS then IMO
> they've made their intention perfectly clear.  They'd expect it to
> create an index sans the unique constraint.  Ignoring the user's
> intention and copying the index as-is (including the unique
> constraint) would be unfriendly.
> 
> Unless the SQL spec demands that we do so?

SQL:2008, like its predecessors, does not mention indexing at all.

Cheers,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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