From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michel Pelletier <pelletier.michel@gmail.com>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Using Expanded Objects other than Arrays from plpgsql
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Comments: In-reply-to Michel Pelletier <pelletier.michel@gmail.com>
	message dated "Thu, 31 Oct 2024 16:41:48 -0700"
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Date: Fri, 01 Nov 2024 18:20:09 -0400
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Michel Pelletier <pelletier.michel@gmail.com> writes:
> Here's two backtraces from gdb from this function:
> CREATE OR REPLACE FUNCTION test2(graph matrix)
>     RETURNS bigint LANGUAGE plpgsql AS
>     $$
>     BEGIN
>     perform set_element(graph, 1, 1, 1);
>     RETURN nvals(graph);
>     end;
>     $$;

Well, you shouldn't be using PERFORM.  Not only does it not do the
right thing, but it's not optimized for expanded objects at all:
they'll get flattened both on the way into the statement and on
the way out.  Try it with

     graph := set_element(graph, 1, 1, 1);
     RETURN nvals(graph);

			regards, tom lane