Grouping intersecting lines

ST_ClusterIntersecting.sql

-- TIL: Create groups of intersecting lines (split by type)
-- first, create some example intersecting and non-intersecting lines
  WITH lines(id, geom, type) AS (
    VALUES (1, 'LINESTRING(1 1,3 1)'::geometry, 'type_A'),
           (2, 'LINESTRING(2 1,2 2)'::geometry, 'type_A'),
           (3, 'LINESTRING(3 2,4 2)'::geometry, 'type_A'),
           (4, 'LINESTRING(3 1,3 2)'::geometry, 'type_B'),
           (5, 'LINESTRING(3 2,3 3)'::geometry, 'type_B')
  )
  SELECT type, ST_AsText(
           ST_CollectionHomogenize( -- convert to single and multi-linestrings
             unnest(ST_ClusterIntersecting(geom)) -- create collections, put intersecting geoms together
           )
          )
    FROM lines
GROUP BY type; -- don't aggregate geoms of a different type

-- thanks Claas Leiner for asking: https://lists.fossgis.de/pipermail/fossgis-talk-liste/2019-June/010055.html