From: Tom Lane <tgl@sss.pgh.pa.us>
To: jbe-mlist@magnetkern.de
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18693: Column names not set when using SELECT STRICT INTO
 with RECORD type
In-reply-to: <18693-65968418890877b4@postgresql.org>
References: <18693-65968418890877b4@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Wed, 06 Nov 2024 18:05:53 +0000"
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Date: Wed, 06 Nov 2024 17:30:02 -0500
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PG Bug reporting form <noreply@postgresql.org> writes:
> I used the following SQL code:

> CREATE TABLE tbl (a TEXT, b TEXT);

> CREATE FUNCTION "buggy"() RETURNS VOID LANGUAGE plpgsql AS $$
>   DECLARE
>     t tbl%ROWTYPE;
>     r RECORD;
>   BEGIN
>     SELECT a, b INTO t FROM (SELECT 'A' AS a, 'B' AS b) AS q;
>     RAISE NOTICE 'non-strict t = %', t;
>     RAISE NOTICE 'non-strict t.a = %', t.a;
>     RAISE NOTICE 'non-strict t.b = %', t.b;
>     SELECT a, b STRICT INTO t FROM (SELECT 'A' AS a, 'B' AS b) AS q;
>     RAISE NOTICE 'STRICT t = %', t;
>     RAISE NOTICE 'STRICT t.a = %', t.a;
>     RAISE NOTICE 'STRICT t.b = %', t.b;
>     SELECT a, b INTO r FROM (SELECT 'A' AS a, 'B' AS b) AS q;
>     RAISE NOTICE 'non-strict r = %', r;
>     RAISE NOTICE 'non-strict r.a = %', r.a;
>     RAISE NOTICE 'non-strict r.b = %', r.b;
>     SELECT a, b STRICT INTO r FROM (SELECT 'A' AS a, 'B' AS b) AS q;
>     RAISE NOTICE 'STRICT r = %', r;
>     RAISE NOTICE 'STRICT r.a = %', r.a;
>     RAISE NOTICE 'STRICT r.b = %', r.b;
>   END;
> $$;

You have the syntax wrong: what you intended (I presume) is

     SELECT a, b INTO STRICT r FROM (SELECT 'A' AS a, 'B' AS b) AS q;

With what you wrote, the STRICT is taken as an output column alias of
the outer SELECT, as if the command were

     SELECT a, b AS "strict" INTO r FROM (SELECT 'A' AS a, 'B' AS b) AS q;

The alias makes no difference when assigning to "t", since its column
names are predetermined.  But when assigning to "r", the second column
winds up being named "strict" not "b".  You can demonstrate this with

    SELECT a, b STRICT INTO r FROM (SELECT 'A' AS a, 'B' AS b) AS q;
    RAISE NOTICE 'STRICT r = %', r;
    RAISE NOTICE 'STRICT r.a = %', r.a;
    RAISE NOTICE 'STRICT r.strict = %', r."strict";

(It's kind of annoying that "strict" has to be double-quoted
in the RAISE NOTICE, especially since you get a rather misleading
error if it isn't.  But that seems like a different discussion.)

			regards, tom lane