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Re: ERROR: cannot start subtransactions during a parallel operation - Mailing list pgsql-hackers

From Mai Peng
Subject Re: ERROR: cannot start subtransactions during a parallel operation
Date
Msg-id 7772057A-8318-49AA-A6EB-221C94A871D6@webedia-group.com
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In response to Re: ERROR: cannot start subtransactions during a parallel operation  (Mai Peng <maily.peng@webedia-group.com>)
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Hi all, 
Sorry for the late reply.
I could handle the pb by transforming my function check ( with an exception ) by a simple sql immutable function.
Function before
CREATE OR REPLACE FUNCTION test_id(ltree[])
RETURNS boolean AS
$BODY$
DECLARE
id public.ltree;
BEGIN
FOR id IN SELECT unnest($1) LOOP
PERFORMl id::id;
IF () THEN
RETURN FALSE;
END IF;
END LOOP;
RETURN TRUE;
EXCEPTION
WHEN OTHERS THEN RETURN FALSE;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;

AFTER
CREATE OR REPLACE FUNCTION test_Id(ltree[])
RETURNS boolean AS
$BODY$
SELECT NOT EXISTS (
SELECT 1
FROM unnest ($1) id
WHERE id<>id::id
)
$BODY$
LANGUAGE sql IMMUTABLE STRICT;


Le 1 juil. 2018 à 11:02, Mai Peng <maily.peng@webedia-group.com> a écrit :

Hello, how could I relax the subtransaction restriction, I used the Parallel Unsafe option, but still have the same issue. 
Rgds.

Le ven. 29 juin 2018 20:47, Andres Freund <andres@anarazel.de> a écrit :
Hi,

On 2018-06-29 20:37:23 +0200, Tomas Vondra wrote:
> My guess is that it's a PL/pgSQL function with an EXCEPTION block, and
> there's no easy way to "fix" that.

Obviously not going to immediately help the OP, but I do think we should
be able to relax the subtransaction restriction around parallelism
without too much work.  Can't allow xids to be assigned, but that's
probably ok for a lot of exception handling cases.

Greetings,

Andres Freund

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