From: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
---|---|
To: | Darren Duncan <darren(at)darrenduncan(dot)net> |
Cc: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: bad variable subst after "AS" |
Date: | 2010-09-16 06:42:23 |
Message-ID: | AANLkTi=r_bGFtNhjggs87HqyRzM9oRCERA4GziKfApx_@mail.gmail.com |
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Lists: | pgsql-hackers |
Hello
2010/9/16 Darren Duncan <darren(at)darrenduncan(dot)net>:
> I don't know if this is a bug or not, but if not, it looks like a misfeature
> ...
>
> When executing the following in Pg 8.4.4:
>
> CREATE OR REPLACE FUNCTION f () RETURNS TABLE(a1 INTEGER) AS
> $BODY$
> BEGIN
> RETURN QUERY SELECT a0 AS a1 FROM rv;
> RETURN;
> END;
> $BODY$
> LANGUAGE plpgsql;
>
It's not a bug - just you cannot use a variable there. Table name,
column names are specified in planner time, and cannot be
parametrized.
Regards
Pavel Stehule
p.s. you can use a dynamic SQL - EXECUTE statement - RETURN QUERY
EXECUTE - but it doesn't help you, because you cannot overwrite a
function definition.
> ... I get this error:
>
> ERROR: syntax error at or near "$1"
> SQL state: 42601
>
> My impression of this is that Pg is treating the "a1" after the "AS" like it
> was
> a variable reference and so substituted it for $1.
>
> Now that just seems wrong to me. I can understand either "a0" or "rv"
> getting a
> substitution, but something following an "AS" being substituted is just
> wrong.
>
> Is that a bug and if not then what is the rationale for working that way,
> and
> can it be changed?
>
> Meanwhile, what is the best way to write f to work around this misbehavior?
>
> Thank you.
>
> -- Darren Duncan
>
>
> --
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