Re: plpgsql - DECLARE - cannot to use %TYPE or %ROWTYPE for composite types - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: plpgsql - DECLARE - cannot to use %TYPE or %ROWTYPE for composite types
Date
Msg-id CAFj8pRCZivm3XsoqWTdRO0a9emJognoPL=mNSW7jCeOMcf67xw@mail.gmail.com
Whole thread Raw
In response to plpgsql - DECLARE - cannot to use %TYPE or %ROWTYPE for composite types  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: plpgsql - DECLARE - cannot to use %TYPE or %ROWTYPE for composite types  (Jim Nasby <Jim.Nasby@BlueTreble.com>)
Re: plpgsql - DECLARE - cannot to use %TYPE or %ROWTYPE for composite types  (Artur Zakirov <a.zakirov@postgrespro.ru>)
List pgsql-hackers


2015-10-19 9:52 GMT+02:00 Pavel Stehule <pavel.stehule@gmail.com>:
Hi,

We cannot to declare variable with referenced type on other composite variable. This limit is probably artificial, because any composite type is any type too in PostgreSQL.

The issue:

referencing on composite variables doesn't work

do $$ declare x int; y x%type; begin end; $$; -- ok
do $$ declare x pg_class; y x%type; begin end; $$; -- invalid type name "x%type"
do $$ declare x pg_class; y x%rowtype; begin end; $$; -- relation "x" does not exist

The %ROWTYPE needs a record in pg_class. Probably we should not to change it. The change can bring a compatibility issues. So there are two possibilities:

1. %TYPE can be used for any kind of variables. This behave will be consistent with polymorphic parameters - we have "anyelement", and we have not "anyrow".

2. introduce new keyword - %RECTYPE .. it can work, but there will be gap between polymorphic parameters.

Comments, notices?


Hi

I am sending patch that enables to use references to polymorphic parameters of row types. Another functionality is possibility to get array or element type of referenced variable. It removes some gaps when polymorphic parameters are used.

 create type test_composite_type as (x int, y int);
create or replace function test_simple(src anyelement)
returns anyelement as $$
declare dest src%type;
begin
  dest := src;
  return dest;
end;
$$ language plpgsql;
select test_simple(10);
 test_simple
-------------
          10
(1 row)

select test_simple('hoj'::text);
 test_simple
-------------
 hoj
(1 row)

select test_simple((10,20)::test_composite_type);
 test_simple
-------------
 (10,20)
(1 row)

create or replace function test_poly_element(x anyelement)
returns anyarray as $$
declare result x%arraytype;
begin
  result := ARRAY[x];
  raise notice '% %', pg_typeof(result), result;
  return result;
end;
$$ language plpgsql;
select test_poly_element(1);
NOTICE:  integer[] {1}
 test_poly_element
-------------------
 {1}
(1 row)

select test_poly_element('hoj'::text);
NOTICE:  text[] {hoj}
 test_poly_element
-------------------
 {hoj}
(1 row)

select test_poly_element((10,20)::test_composite_type);
NOTICE:  test_composite_type[] {"(10,20)"}
 test_poly_element
-------------------
 {"(10,20)"}
(1 row)

create or replace function test_poly_array(x anyarray)
returns anyelement as $$
declare result x%elementtype;
begin
  result := x[1];
  raise notice '% %', pg_typeof(result), result;
  return result;
end;
$$ language plpgsql;
select test_poly_array(ARRAY[1]);
NOTICE:  integer 1
 test_poly_array
-----------------
               1
(1 row)

select test_poly_array(ARRAY['hoj'::text]);
NOTICE:  text hoj
 test_poly_array
-----------------
 hoj
(1 row)

select test_poly_array(ARRAY[(10,20)::test_composite_type]);
NOTICE:  test_composite_type (10,20)
 test_poly_array
-----------------
 (10,20)
(1 row)

Regards

Pavel

 
Regards

Pavel



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