From: | Marc Cousin <cousinmarc(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-docs(at)postgresql(dot)org |
Subject: | Re: CREATE OPERATOR and precedence |
Date: | 2010-07-08 15:42:22 |
Message-ID: | 201007081742.22830.cousinmarc@gmail.com |
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Lists: | pgsql-docs |
The Thursday 08 July 2010 16:31:41, Tom Lane wrote :
> Marc Cousin <cousinmarc(at)gmail(dot)com> writes:
> > I just got caught by a precedence problem with CREATE OPERATOR.
> >
> > Obviously, it was mostly my fault (I didn't think of the precedence of my
> > operator at all), but I didn't find anything in the CREATE OPERATOR
> > documentation about it either.
>
> CREATE OPERATOR has nothing to say on the subject because operator
> precedences are hard-wired into the parser and can't be changed by
> CREATE OPERATOR. See
>
> http://www.postgresql.org/docs/8.4/static/sql-syntax-lexical.html#SQL-PRECE
> DENCE
>
> regards, tom lane
Yes, that's what I found out, afterwards.
From a technical point of view, I obviously totally agree, operators have no
control over precedence, but I was only reporting this because I thought that
it might be helpful to put something like a pointer to this table in the
CREATE OPERATOR doc.
From the user's point of view, even if precedence is hard-wired in the parser,
a note about it could help here, if only as a reminder. The first thing I
thought when facing the problem was : "how do I specify the precedence ?". I
found out I couldn't, but a pointer or a note would have been even easier.
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