Unexpected behaviour of a RAISE statement in an IMMUTABLE function
| От | Joel Mukuthu |
|---|---|
| Тема | Unexpected behaviour of a RAISE statement in an IMMUTABLE function |
| Дата | |
| Msg-id | CAAT35tGXUYgjjViNZ5+9nFkrOcmgE4ce+VvekjgKDy_C38RT2g@mail.gmail.com обсуждение исходный текст |
| Ответы |
Re: Unexpected behaviour of a RAISE statement in an IMMUTABLE function
Re: Unexpected behaviour of a RAISE statement in an IMMUTABLE function |
| Список | pgsql-bugs |
Hi,
Given the following two functions, where the only difference between them is that one is VOLATILE while the other is IMMUTABLE:
CREATE FUNCTION raise_exception_volatile(IN err_message text)
RETURNS void
LANGUAGE 'plpgsql'
VOLATILE
AS $BODY$
BEGIN
RAISE EXCEPTION
USING MESSAGE = err_message;
END;
$BODY$;
CREATE FUNCTION raise_exception_immutable(IN err_message text)
RETURNS void
LANGUAGE 'plpgsql'
IMMUTABLE
AS $BODY$
BEGIN
RAISE EXCEPTION
USING MESSAGE = err_message;
END;
$BODY$;
1. This raises an exception, as expected:
SELECT raise_exception_volatile('foo') WHERE true;
-- ERROR: foo
-- CONTEXT: PL/pgSQL function raise_exception_volatile(text) line 3 at RAISE
2. This does not raises an exception, as expected:
SELECT raise_exception_volatile('foo') WHERE false;
3. This raises an exception, as expected:
SELECT raise_exception_immutable('foo') WHERE true;
-- ERROR: foo
-- CONTEXT: PL/pgSQL function raise_exception_immutable(text) line 3 at RAISE
4. This raises an exception that was surprising to me:
SELECT raise_exception_immutable('foo') WHERE false;
-- ERROR: foo
-- CONTEXT: PL/pgSQL function raise_exception_immutable(text) line 3 at RAISE
5. This does not raises an exception, that was also surprising to me:
SELECT raise_exception_immutable(format('foo')) WHERE false;
Tested on a postgres:12.8-alpine docker container.
I couldn't find any notes about this behaviour in the postgres docs (https://www.postgresql.org/docs/12/sql-createfunction.html and https://www.postgresql.org/docs/12/plpgsql-errors-and-messages.html) and in fact, the documentation on CREATE FUNCTION suggests to me that this function should be marked as IMMUTABLE.
Is this behaviour expected?
Best regards,
Joel Mukuthu.
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