Re: unnest array of row type

2012/1/12 Merlin Moncure <mmoncure@gmail.com>:
> On Thu, Jan 12, 2012 at 8:47 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>> 2012/1/12  <seiliki@so-net.net.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

sure - this is better

Pavel