postgis - Split Line at intersection and attach attributes

I want to slit line at intersection and attach attributes and export I have roads table with columns id,road_name,road_type,geom with 2115 records. I try using this query - select st_astext((st_dump(st_union(geom))).geom) from roads; it successfully splits the line gives 5114 records but when i am trying to attach attributes it fails select id,road_name,road_type,st_astext((st_dump(st_union(geom))).geom) from roads;

I need to split line at intersection also keep attributes means line 1 divide in 3 having same id is 1 , road_name is abc similar to line 2 divide in 2 having same id is 2 , road_name is xyz and so on.

Answer

You could also use PostGIS topologies, they do just that.

http://blog.mathieu-leplatre.info/use-postgis-topologies-to-clean-up-road-networks.html

You can join your road table on topology edges, using this query:

SELECT r.road_type, r.road_name, e.geom
FROM roads_topo.edge e,

     roads_topo.relation rel,
     roads r
WHERE e.edge_id = rel.element_id
  AND rel.topogeo_id = (r.topo_geom).id

I will add that part to the article. Thanks for insisting btw, I could dig into topology internal tables and attributes :)