postgresql: INSERT INTO ... (SELECT * ...)

As Henrik wrote you can use dblink to connect remote database and fetch result. For example:

psql dbtest
CREATE TABLE tblB (id serial, time integer);
INSERT INTO tblB (time) VALUES (5000), (2000);

psql postgres
CREATE TABLE tblA (id serial, time integer);

INSERT INTO tblA
    SELECT id, time 
    FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
    AS t(id integer, time integer)
    WHERE time > 1000;

TABLE tblA;
 id | time 
----+------
  1 | 5000
  2 | 2000
(2 rows)

PostgreSQL has record pseudo-type (only for function's argument or result type), which allows you query data from another (unknown) table.

Edit:

You can make it as prepared statement if you want and it works as well:

PREPARE migrate_data (integer) AS
INSERT INTO tblA
    SELECT id, time
    FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
    AS t(id integer, time integer)
    WHERE time > $1;

EXECUTE migrate_data(1000);
-- DEALLOCATE migrate_data;

Edit (yeah, another):

I just saw your revised question (closed as duplicate, or just very similar to this).

If my understanding is correct (postgres has tbla and dbtest has tblb and you want remote insert with local select, not remote select with local insert as above):

psql dbtest

SELECT dblink_exec
(
    'dbname=postgres',
    'INSERT INTO tbla
        SELECT id, time
        FROM dblink
        (
            ''dbname=dbtest'',
            ''SELECT id, time FROM tblb''
        )
        AS t(id integer, time integer)
        WHERE time > 1000;'
);

I don't like that nested dblink, but AFAIK I can't reference to tblB in dblink_exec body. Use LIMIT to specify top 20 rows, but I think you need to sort them using ORDER BY clause first.

If you want insert into specify column:

INSERT INTO table (time)
(SELECT time FROM 
    dblink('dbname=dbtest', 'SELECT time FROM tblB') AS t(time integer) 
    WHERE time > 1000
);