From: Tom Lane <tgl@sss.pgh.pa.us>
To: Vik Fearing <vik.fearing@2ndquadrant.com>
cc: Andrew Gierth <andrew@tao11.riddles.org.uk>, pgsql-hackers@postgresql.org
Subject: Re: Fix for FETCH FIRST syntax problems
In-reply-to: <03da97fc-9d6b-cbe1-c28f-cee7c1ba5c38@2ndquadrant.com>
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 <22981.1526770675@sss.pgh.pa.us>
 <03da97fc-9d6b-cbe1-c28f-cee7c1ba5c38@2ndquadrant.com>
Comments: In-reply-to Vik Fearing <vik.fearing@2ndquadrant.com>
	message dated "Sun, 20 May 2018 01:27:30 +0200"
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Date: Sat, 19 May 2018 19:41:10 -0400
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Vik Fearing <vik.fearing@2ndquadrant.com> writes:
> On 20/05/18 00:57, Tom Lane wrote:
>> Also, why'd you back off "must write" to "should write" in the docs?
>> This doesn't make the parens any more optional than before.

> It certainly does.  It allows this now:
> PREPARE foo AS TABLE bar FETCH FIRST $1 ROWS ONLY;

No, it makes the parens omittable in the cases specified in the previous
sentence.  The sentence I'm complaining about is describing other cases,
in which they're still required.

> I'm +1 for backpatching it.  It may be operating as designed by PeterE
> ten years ago, but it's not operating as designed by the SQL standard.

By that argument, *anyplace* where we're missing a SQL-spec feature
is a back-patchable bug.  I don't buy it.

It may be that this fix is simple and safe enough that the risk/reward
tradeoff favors back-patching, but I think you have to argue it as a
favorable tradeoff rather than just saying "this isn't per standard".
Consider: if Andrew had completely rewritten gram.y to get the same
visible effect, would you think that was back-patchable?

			regards, tom lane