Re: Function overloading - Mailing list pgsql-novice
From | Rynell Wesson |
---|---|
Subject | Re: Function overloading |
Date | |
Msg-id | Pine.LNX.4.21.0012100013410.30457-100000@isle-of-jura.cs.utexas.edu Whole thread Raw |
In response to | Re: Function overloading (Tom Lane <tgl@sss.pgh.pa.us>) |
Responses |
Re: Function overloading
("Robert B. Easter" <reaster@comptechnews.com>)
|
List | pgsql-novice |
On Sat, 9 Dec 2000, Tom Lane wrote: > Rynell Wesson <rwesson@cs.utexas.edu> writes: > > I keep getting the following error. > > > psql:fdm:11: ERROR: Function 'foo(unknown, unknown)' does not exist > > That could only come out when you write > > select foo('string', 'string') > > and there is more than one possible candidate for foo(). The thing to > realize here is that Postgres does not assume that 'string' is a string. > Rather, it is a literal of as-yet-undetermined type. If the particular > foo() function can be identified uniquely, then the system can infer > what type the unknown-type literal should be converted to. Otherwise > it gets unhappy. > > In the example you've given, > select foo(text('testing'), text('testing')); > ought to work fine to select the foo(text,text) function. It does work > when I try it. I wonder whether you are looking for the problem in the > wrong place. Is it possible that the error report is actually coming > from trying to evaluate the function body? What did you put in the > body, anyway? Unless I missed something, the function bodies do not appear to be the problem. They have both been tested seperately without any problems. It seems as if there is a problem with the compiler's semantic analysis phase. Here are the function bodies. CREATE FUNCTION foo(text, text) RETURNS NUMERIC AS ' DECLARE p_qstn ALIAS FOR $1; p_fname ALIAS FOR $2; v_fid foq.fid%TYPE; v_qid foq.qid%TYPE; v_qnum foq.qnum%TYPE; BEGIN SELECT id INTO v_qid FROM qwert WHERE qstn = p_qstn; SELECT id, nqs INTO v_fid, v_qnum FROM farm WHERE name = p_fname; v_qnum := v_qnum + 1; UPDATE farm SET nqs = nqs + 1 WHERE name = p_fname; INSERT INTO foq (fid, qid, qnum) VALUES (v_fid, v_qid, v_qnum); RETURN 0; END;' LANGUAGE 'plpgsql'; CREATE FUNCTION foo(int4, int4) RETURNS NUMERIC AS ' DECLARE p_qid ALIAS FOR $1; p_fid ALIAS FOR $2; v_qnum foq.qnum%TYPE; BEGIN SELECT nqs INTO v_qnum FROM farm WHERE id = p_fid; v_qnum := v_qnum + 1; UPDATE farm SET nqs = nqs + 1 WHERE id = p_fid; INSERT INTO foq (fid, qid, qnum) VALUES (p_fid, p_qid, v_qnum); RETURN 0; END;' LANGUAGE 'plpgsql'; > > BTW, Postgres 7.1 has been tweaked to be more willing to assume that > an unidentified-type literal is a string datatype, when it can't make > a unique decision otherwise. So in 7.1 you'll get the result you > expected from "select foo('string', 'string')". But the form with > the explicit casts should have worked anyway. > > regards, tom lane >
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