Re: unnest array of row type

[seiliki@xxxxxxxxxxxxx]

What I really intend to do is slightly more complicate than the original code. I need to iterate RECORD variable in PL/pgSQL. By combining both ideas from Pavel and Merlin, I get the following working function.

CREATE FUNCTION test() RETURNS VOID AS $$
DECLARE
	rec RECORD;
BEGIN
	CREATE TABLE test (c1 SMALLINT,c2 TEXT,c3 TEXT);
	CREATE TYPE my_row_type AS (c1 SMALLINT,c2 TEXT);

	FOR rec IN
	SELECT ARRAY[ROW(1::SMALLINT,'a'::TEXT),ROW(2::SMALLINT,'b'::TEXT)] AS array_of_rows,'x' AS x
	LOOP
		INSERT INTO test
		SELECT (r).c1,(r).c2,rec.x
		FROM (
			SELECT (c1,c2)::my_row_type AS r
			FROM UNNEST(rec.array_of_rows) AS (c1 SMALLINT,c2 TEXT)
		) s;
	END LOOP;
	DROP TYPE my_row_type;
	DROP TABLE test;
END $$ LANGUAGE PLPGSQL VOLATILE;

Pavel and Merlin, thank you!

CN
> -----Original Message-----
> From: Merlin Moncure 
> Sent: Fri, Jan 13 2012 01:13:09 CST
> To: Pavel Stehule
> Subject: Re:  unnest array of row type
> 
> On Thu, Jan 12, 2012 at 8:47 AM, Pavel Stehule <pavel.stehule@xxxxxxxxx> wrote:
> > 2012/1/12  <seiliki@xxxxxxxxxxxxx>:
> >> 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
> 
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