BUG #15993: "CREATE OR REPLACE FUNCTION" does not clear search_path

On Fri, Sep 6, 2019 at 08:42:02PM +0000, PG Bug reporting form wrote:

The following bug has been logged on the website:

Bug reference: 15993
Logged by: Alexander Pavlov
Email address: alexander.pavlov.rus@gmail.com
PostgreSQL version: 10.9
Operating system: Debian
Description:

-- this will correctly create function with empty search_path
CREATE OR REPLACE FUNCTION MY_FUNC () RETURNS BOOLEAN AS $$ BEGIN RETURN
TRUE;END;$$ LANGUAGE PLPGSQL;

-- this will correctly update function to have "PUBLIC, MY_SCHEMA" search
path
CREATE OR REPLACE FUNCTION MY_FUNC () RETURNS BOOLEAN AS $$ BEGIN RETURN
TRUE;END;$$ LANGUAGE PLPGSQL SET SEARCH_PATH TO PUBLIC, MY_SCHEMA;

-- this will correctly update function to have "MY_SCHEMA" search path
CREATE OR REPLACE FUNCTION MY_FUNC () RETURNS BOOLEAN AS $$ BEGIN RETURN
TRUE;END;$$ LANGUAGE PLPGSQL SET SEARCH_PATH TO MY_SCHEMA;

-- this will NOT update function to have empty search path, search path will
remain "MY_SCHEMA", as at previous "create or replace" call
CREATE OR REPLACE FUNCTION MY_FUNC () RETURNS BOOLEAN AS $$ BEGIN RETURN
TRUE;END;$$ LANGUAGE PLPGSQL;

So you are saying that CREATE OR REPLACE FUNCTION should not preserve
the SEARCH_PATH. Makes sense to me. Any idea why we coded it this way?
It it part of the "OR REPLACE" goal?

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

Bruce Momjian <bruce@momjian.us> writes:

So you are saying that CREATE OR REPLACE FUNCTION should not preserve
the SEARCH_PATH. Makes sense to me. Any idea why we coded it this way?

We didn't. For me, it works as expected:

... follow example, \sf after each step
regression=# \sf my_func
CREATE OR REPLACE FUNCTION public.my_func()
RETURNS boolean
LANGUAGE plpgsql
SET search_path TO 'my_schema'
AS $function$ BEGIN RETURN
TRUE;END;$function$
regression=# CREATE OR REPLACE FUNCTION MY_FUNC () RETURNS BOOLEAN AS $$ BEGIN RETURN
regression$# TRUE;END;$$ LANGUAGE PLPGSQL;
CREATE FUNCTION
regression=# \sf my_func
CREATE OR REPLACE FUNCTION public.my_func()
RETURNS boolean
LANGUAGE plpgsql
AS $function$ BEGIN RETURN
TRUE;END;$function$

regards, tom lane