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Re: MERGE Specification

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Treat <xzilla@users.sourceforge.net>
Cc: pgsql-hackers@postgresql.org, Decibel! <decibel@decibel.org>, Martijn van Oosterhout <kleptog@svana.org>, Gregory Stark <stark@enterprisedb.com>, Simon Riggs <simon@2ndquadrant.com>, "A.M." <agentm@themactionfaction.com>
Date: 2008-04-25T03:40:22Z
Lists: pgsql-hackers 
Robert Treat <xzilla@users.sourceforge.net> writes:
> Perhaps a better option would be to implement Merge per spec, and then 
> implement a "replace into" command for the oltp scenario.  This way you keep 
> the spec behavior for the spec syntax, and have a clearly non-spec command 
> for non-spec behavior. 

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 recently came across the expression "YAGNI", and think it's probably
pretty relevant to this discussion:
http://en.wikipedia.org/wiki/You_Ain't_Gonna_Need_It

			regards, tom lane