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From: Tom Lane <[email protected]>
To: Michel Pelletier <[email protected]>
Cc: pgsql-general <[email protected]>
Subject: Re: Using Expanded Objects other than Arrays from plpgsql
Date: Sun, 20 Oct 2024 23:46:44 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CACxu=vLXvpzN4X3k+9jsMt6ujuOvFVUSkA80t_cROSsF4y2jQQ@mail.gmail.com>
References: <CACxu=vJaKFNsYxooSnW1wEgsAO5u_v1XYBacfVJ14wgJV_PYeg@mail.gmail.com>
	<[email protected]>
	<CACxu=vLXvpzN4X3k+9jsMt6ujuOvFVUSkA80t_cROSsF4y2jQQ@mail.gmail.com>

Michel Pelletier <[email protected]> writes:
> On Sun, Oct 20, 2024 at 10:13 AM Tom Lane <[email protected]> wrote:
>> But it seems like we could get an easy win by adjusting
>> plpgsql_exec_function along the lines of
>> ...

> I tried this change and couldn't get it to work, on the next line:
>     if (VARATT_IS_EXTERNAL_EXPANDED_RW(DatumGetPointer(var->value)))
> var->value might not be a pointer, as it seems at least from my gdb
> scratching, but say an integer.  This segfaults on non-array but
> non-expandable datum.

Oh, duh --- the typisarray test serves to eliminate pass-by-value
types.  We need the same test that exec_assign_value makes,
!var->datatype->typbyval, before it's safe to apply DatumGetPointer.
So line 549 needs to be more like

-                    if (!var->isnull && var->datatype->typisarray)
+                    if (!var->isnull && !var->datatype->typbyval)

> Another comment that caught my eye was this one:
> https://github.com/postgres/postgres/blob/master/src/pl/plpgsql/src/pl_exec.c#L8304
> Not sure what the implication is there.

Yeah, that's some more unfinished business.  I'm not sure if it
matters to your use-case or not.

BTW, we probably should move this thread to pgsql-hackers.

			regards, tom lane

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