unwrap postgresql array into rows

unnest --> expand an array to a set of rows

unnest(ARRAY[1,2])
1
2

http://www.sqlfiddle.com/#!1/c774a/24

Use unnest. For example:

CREATE OR REPLACE FUNCTION test( p_test text[] )
  RETURNS void AS
$BODY$
BEGIN
  SELECT id FROM unnest( p_test ) AS id;
END;
$BODY$
  LANGUAGE plpgsql IMMUTABLE
  COST 1;

If you have a table users_to_articles like:

And need to explode the articles array so to obtain:

You could run something like that:

CREATE TABLE "users_to_articles" (
  "user_id" SERIAL PRIMARY KEY,
  "articles" INT[]
);

INSERT INTO "users_to_articles" ("articles")
VALUES ('{1,2}'), ('{6,2,7}');

SELECT
  "user_id"
, "article_id"
FROM "users_to_articles", unnest("articles") AS "article_id";

Here is a working sqlfiddle:
http://www.sqlfiddle.com/#!17/c26742/1