Re: Making OFF unreserved

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Making OFF unreserved
Date: 2010-10-22 13:54:47
Message-ID: 21367.1287755687@sss.pgh.pa.us
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> OFF is a reserved keyword. It's not a reserved keyword in the SQL spec,
> and it's not hard to see people using off as a variable or column name,
> so it would be nice to relax that.

While I can see the value of doing something about that, this seems
awfully fragile:

> + /*
> + * OFF is also accepted as a boolean value, but is not listed
> + * here to avoid making it a reserved keyword. All uses of
> + * opt_boolean rule also accept a ColId with the same action -
> + * OFF is handled via that route.
> + */

The production's correctness now depends on how it's used, and there's
no way to prevent somebody from misusing it.

I think it'd be better if you were to refactor the grammar so that ColId
was actually one of the alternatives in this very production (call it
opt_boolean_or_name, or something like that). Then at least there'd be
less of a flavor of action-at-a-distance about the assumption that OFF
was handled in a compatible fashion.

regards, tom lane

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