From: | Ron <ronljohnsonjr(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Practice advice for use of %type in declaring a subprogram's formal arguments |
Date: | 2023-03-10 22:49:52 |
Message-ID: | 8b4850d2-5f97-f0ff-5288-b9861d9e7f72@gmail.com |
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Thread: | |
Lists: | pgsql-general |
On 3/10/23 15:28, Bryn Llewellyn wrote:
> I'm thinking about "language plpgsql" subprograms—but I expect that my
> question can be generalized to cover "language sql" too.
>
> The payload for "create [or replace]" for a "language plpgsql" subprogram
> specifies various metadata elements like its qualified name, list of
> formal arguments and their modes and datatypes, "security invoker/definer"
> and so on together with the enquoted actual PL/pgSQL source text.
>
> When the DDL succeeds, the PL/pgSQL source text is recorded verbatim in
> "pg_proc". But the meaning of everything else is parsed out and
> represented as individual fields in "pg_proc" and other tables like
> "pg_namespace". This is reflected by the canonical form that "\sf" uses,
> for example:
>
> create table s.t(k integer primary key, v integer);
>
> create procedure s.p(k_in in t.k%type, v_in t.v%type)
> language plpgsql
> as $body$
> begin
> /* ... */
> end;
> $body$
>
> \sf s.p
>
> This is the output:
>
> CREATE OR REPLACE PROCEDURE s.p(k_in integer, v_in integer)
> LANGUAGE plpgsql
> AS $procedure$
> begin
> /* ... */
> end;
> $procedure$
>
> This shows that my use of "%type"was consumed at "create" time and then
> recorded in the catalog as what it translated to. The consequence is that
> if the table is dropped and re-created thus:
Here's what happens when you use domains. The first thing I (pun intended)
noticed are the two NOTICE messages. You might have noticed them if your
log_min_messages level was high enough.
CREATE DOMAIN
postgres=# create domain d_counting_ints integer check (value > 0);
CREATE DOMAIN
postgres=#
^
postgres=# drop table if exists foo;
NOTICE: table "foo" does not exist, skipping
DROP TABLE
postgres=# create table foo(pk d_pk, c d_counting_ints);
CREATE TABLE
postgres=#
postgres=# create procedure mypro(p_pk foo.pk%type, p_cnt foo.c%type)
postgres-# language plpgsql
postgres-# as $body$
postgres$# begin
postgres$# raise notice '% %', p_pk, p_cnt;
postgres$# end;
postgres$# $body$
postgres-# ;
NOTICE: type reference foo.pk%TYPE converted to d_pk
NOTICE: type reference foo.c%TYPE converted to d_counting_ints
CREATE PROCEDURE
postgres=#
postgres=# \sf mypro
CREATE OR REPLACE PROCEDURE public.mypro(p_pk d_pk, p_cnt d_counting_ints)
LANGUAGE plpgsql
AS $procedure$
begin
raise notice '% %', p_pk, p_cnt;
end;
$procedure$
--
Born in Arizona, moved to Babylonia.
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