From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
cc: Simon Riggs <simon@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        Andrew Dunstan <andrew.dunstan@2ndquadrant.com>,
        Pavan Deolasee <pavan.deolasee@2ndquadrant.com>,
        Peter Geoghegan <pg@bowt.ie>, Stephen Frost <sfrost@snowman.net>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] MERGE SQL Statement for PG11
In-reply-to: <20180129164422.GE11613@momjian.us>
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 <20180129164422.GE11613@momjian.us>
Comments: In-reply-to Bruce Momjian <bruce@momjian.us>
	message dated "Mon, 29 Jan 2018 11:44:22 -0500"
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Date: Mon, 29 Jan 2018 11:50:02 -0500
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Bruce Momjian <bruce@momjian.us> writes:
> On Mon, Jan 29, 2018 at 04:34:48PM +0000, Simon Riggs wrote:
>> ... If unfinished means it has caveats
>> that is different to unfinished meaning crappy, risky, contentious
>> etc..

> I think the question is how does it handle cases it doesn't support? 
> Does it give wrong answers?  Does it give a helpful error message?  Can
> you summarize that?

What I was reacting to was the comments just upthread that it doesn't
yet handle partitions or RLS.  Those things don't seem optional to me.
Maybe they're small additions, but if so why aren't they done already?

Also, as far as phased development goes: Simon's drawing analogies
to things like parallel query, which we all understood had to be
done over multiple dev cycles because they were too big to finish
in one cycle.  I don't think MERGE qualifies: there seems no good
reason why it can't be done, full stop, in the first release where
it appears.

			regards, tom lane