From: Tom Lane <tgl@sss.pgh.pa.us>
To: rir <rirans@comcast.net>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: pgsql-docs@lists.postgresql.org
Subject: Re: small patch
Date: Thu, 07 Oct 2021 16:24:16 -0400
Message-ID: <175281.1633638256@sss.pgh.pa.us> (raw)
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rir <rirans@comcast.net> writes:
> On Thu, Oct 07, 2021 at 07:58:47AM +0200, Laurenz Albe wrote:
>> Can you think of a way to modify the syntax diagram so that it
>> expresses that and still remains comprehensible?
> For myself,
> 'FETCH [ <direction> [ FROM | IN ] ] <cursor_name>'
> clearly indicates that 'direction' is optional.
Right, but if we don't say that <direction> can be
empty, then this diagram disallows
FETCH FROM cursor_name
which in fact is legal. I think however that we could make it read
FETCH [ <direction> ] [ FROM | IN ] <cursor_name>'
and have a correct description without requiring <direction>
to be allowed to be empty.
BTW, as it stands, the diagram is ambiguous
because there are two ways to parse
FETCH cursor_name
... is <direction> present but empty, or omitted altogether?
regards, tom lane
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To: pgsql-docs@postgresql.org
Cc: tgl@sss.pgh.pa.us, rirans@comcast.net, laurenz.albe@cybertec.at, pgsql-docs@lists.postgresql.org
Subject: Re: small patch
In-Reply-To: <175281.1633638256@sss.pgh.pa.us>
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