Convert a Linestring into a set of two-point segments

segments.sql

    CREATE TABLE lines ( 
      gid integer primary key, 
      geom geometry(Linestring, 4326)
    );

    INSERT INTO lines VALUES (1, 'SRID=4326;LINESTRING(1 1, 2 2, 3 3, 4 4)');
    INSERT INTO lines VALUES (2, 'SRID=4326;LINESTRING(0 1, 0 2, 0 3, 0 4)');

    WITH 
    dumps AS ( 
      SELECT gid, ST_DumpPoints(geom) AS pt FROM lines
    ), 
    pts AS (
      SELECT gid, (pt).geom, (pt).path[1] AS vert FROM dumps
    ) 
    SELECT a.gid, ST_AsText(ST_MakeLine(ARRAY[a.geom, b.geom])) AS geom, 
           a.vert, b.vert 
    FROM pts a, pts b 
    WHERE a.gid = b.gid AND a.vert = b.vert-1 AND b.vert > 1;
    
    -- High performance alternative
    WITH segments AS (
    SELECT gid, ST_AsText(ST_MakeLine(lag((pt).geom, 1, NULL) OVER (PARTITION BY gid ORDER BY gid, (pt).path), (pt).geom)) AS geom
      FROM (SELECT gid, ST_DumpPoints(geom) AS pt FROM lines) as dumps
    )
    SELECT * FROM segments WHERE geom IS NOT NULL;

What about using DumpPoints result into ST_Split function? See my fork https://gist.github.com/caiohamamura/d53c77887df137159d800701adc7cdf2