From: Richard Huxton <dev@archonet.com>
To: Emil Rachovsky <zsevgymko@yahoo.com>
Cc: pgsql-general@postgresql.org <pgsql-general@postgresql.org>
Cc: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: problem with overloading the "coalesce" function
Date: Mon, 06 Mar 2006 11:29:56 +0000
Message-ID: <440C1D34.6060308@archonet.com> (raw)
In-Reply-To: <20060306111333.83983.qmail@web54306.mail.yahoo.com>
References: <20060306111333.83983.qmail@web54306.mail.yahoo.com>
Emil Rachovsky wrote:
>
> --- Richard Huxton <dev@archonet.com> wrote:
>
>> Emil Rachovsky wrote:
>>> Hi,
>>> I am trying to overload the "coalesce" function to
>>> accept an integer and a string. Here it is :
>>>
>>> CREATE OR REPLACE FUNCTION "coalesce"(a int4, b
>>> "varchar")
>>> RETURNS "varchar" AS
>> ...
>>> I have added it to pg_catalog, but still I cant't
>> use
>>> it, I get an error on the second parameter
>> What is the error?
>
> The error is : invalid input syntax for integer
> That is,it expects an integer as a second parameter,
> since the first is an integer.
Hmm - looking at the source (and \df in psql) it seems the basic problem
is that COALESCE() isn't a function. It has its own code in the parser
and its own expression-node. So - your function never gets called
because the parser sees coalesce() and doesn't build a function - it
builds a coalesce-expression.
It should work fine if you rename your function of course.
HTH
--
Richard Huxton
Archonet Ltd
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Subject: Re: problem with overloading the "coalesce" function
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