Date: Fri, 9 Apr 2021 20:30:14 -0700
From: Noah Misch <noah@leadboat.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Julien Rouhaud <rjuju123@gmail.com>,
	Michael Paquier <michael@paquier.xyz>,
	Andres Freund <andres@anarazel.de>,
	Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
	Jaime Casanova <jcasanov@systemguards.com.ec>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: SQL-standard function body
Message-ID: <20210410033014.GA993491@rfd.leadboat.com>
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On Fri, Apr 09, 2021 at 12:09:43PM -0400, Tom Lane wrote:
> Finally, 0003 might be a bit controversial: it changes the stored
> prosrc for new-style SQL functions to be the query text of the CREATE
> FUNCTION command.  The main argument I can see being made against this
> is that it'll bloat the pg_proc entry.  But I think that that's
> not a terribly reasonable concern

Such storage cost should be acceptable, but ...

> The real value of 0003 of course would be to get an error cursor at
> runtime

A key benefit of $SUBJECT is the function body following DDL renames:

create table foo ();
insert into foo default values;
create function count_it() returns int begin atomic return (select count(*) from foo); end;
select count_it();
insert into foo default values;
alter table foo rename to some_new_long_table_name;
select count_it();  -- still works

After the rename, any stored prosrc is obsolete.  To show accurate error
cursors, deparse prosqlbody and use that in place of prosrc.