geometry - In PostGIS: how to split linestrings into their individual segments?

I have one table with many linestrings and I want to make a new table containing the individual segments of all the linestrings, no matter if they are grouped line per line or not.

This is my table, really simple:

table myline (

  the_geom geometry(LineString,4326),
  id integer,
)

I already tried with no results code like this:

SELECT ST_AsText( ST_MakeLine(sp,ep) )
FROM
-- extract the endpoints for every 2-point line segment for each linestring
(SELECT
  ST_PointN(geom, generate_series(1, ST_NPoints(geom)-1)) as sp,

  ST_PointN(geom, generate_series(2, ST_NPoints(geom)  )) as ep
FROM
   -- extract the individual linestrings
  (SELECT (ST_Dump(ST_Boundary(ll.the_geom))).geom
   FROM mylines ll
   -- eliminate 0 length linestring 
    where st_x(st_startpoint(ll.the_geom))<> st_x(st_endpoint(ll.the_geom))
   ) AS linestrings
) AS segments;

and this:

select st_astext(st_makeline(st_pointn(a.line, a.idx), st_pointn(a.line, a.idx+1))) as txt
from (select the_lines as line, traj_id as idx from mylines) as a

I have to say that I created the lines from a set of GPS points I have from the dataset, so another solution could be create segment lines from the points directly.