Re: unnest array of row type

On Thu, Jan 12, 2012 at 8:47 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> 2012/1/12  <seiliki(at)so-net(dot)net(dot)tw>:
>> Hi!
>>
>> CREATE TYPE my_row_type AS (c1 SMALLINT,c2 TEXT);
>>
>> CREATE FUNCTION tmp_get_c1(my_row_type) RETURNS SMALLINT AS 'SELECT $1.c1' LANGUAGE SQL;
>>
>> CREATE FUNCTION tmp_get_c2(my_row_type) RETURNS TEXT AS 'SELECT $1.c2' LANGUAGE SQL;
>>
>> CREATE TABLE test (c1 SMALLINT,c2 TEXT,c3 TEXT);
>>
>> INSERT INTO test
>> SELECT tmp_get_c1(r),tmp_get_c2(r),'x'
>> FROM (
>>        SELECT UNNEST(ARRAY[ROW(1::SMALLINT,'a'::TEXT),ROW(2::SMALLINT,'b'::TEXT)]) AS r
>> ) s;
>>
>> I get error "record type has not been registered" from the previous INSERT.
>>
>> I have tested version 9.1 and have confirmed that PL/PGSQL "FOREACH ... IN ARRAY ... LOOP ... END LOOP;" does the job. Because I wonder "INSERT INTO ... SELECT ... FROM" being faster than "LOOP ... END LOOP;", I raise this question.
>>
>
> insert into test select tmp_get_c1(r), tmp_get_c2(r), 'x' from (SELECT
> (x,y)::my_row_type as r from
> UNNEST(ARRAY[ROW(1::SMALLINT,'a'::TEXT),ROW(2::SMALLINT,'b'::TEXT)])
> AS (x smallint, y text)) x;

I don't think the tmp_get* functions are necessary (and even if they
were, you should mark them 'immutable'). Also that's unnecessarily
verbose. I would write it like this:

INSERT INTO test SELECT (r).c1, (r).c2, 'x' FROM
(
SELECT UNNEST(ARRAY[ROW(1,'a'),ROW(2,'b')]::my_row_type[]) r
) x;

merlin