Re: MERGE Specification

Martijn van Oosterhout <kleptog@svana.org>

From: Martijn van Oosterhout <kleptog@svana.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Treat <xzilla@users.sourceforge.net>, pgsql-hackers@postgresql.org, Decibel! <decibel@decibel.org>, Gregory Stark <stark@enterprisedb.com>, Simon Riggs <simon@2ndquadrant.com>, "A.M." <agentm@themactionfaction.com>
Date: 2008-04-25T08:36:27Z
Lists: pgsql-hackers
On Thu, Apr 24, 2008 at 11:40:22PM -0400, Tom Lane wrote:
> In that case, it's a fair question to ask just who will use the "spec"
> syntax.  As far as I can tell from years of watching the mailing lists,
> there is plenty of demand for a concurrent-safe insert-or-update
> behavior, and *exactly zero* demand for the other.  I challenge you to
> find even one request for the "spec" behavior in the mailing list
> archives.  (Simon doesn't count.)

I could have used something like this a few years ago. I don't think it
would get mentioned on the lists, because frankly it's not something I
would've expected a DBMS to handle internally. Certainly I'd never
heard of the MERGE command until recently. I just wrote a program to do
it (and no, race conditions wern't an issue).

Making a race condition free version is fine, just as long as merging
on a condition without a unique index is also supported.

Have a nice day,
-- 
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while 
> boarding. Thank you for flying nlogn airlines.