Sometimes you need to convert a PostGIS line into a multipoint geometry. I mean, how else did you find this?
SELECT ST_Union(
ARRAY(
SELECT (ST_DumpPoints(linestringcolumn)).geom
FROM atable
)
);
Just kidding, use ST_Points(). Why ST_MultiPoint() does not do this is a mystery to my tiny brain. I would ask Dan Baston, but his answer would probably fracture my mental model of reality, and I don't have time to reconstruct it right now.
SELECT ST_Points(linestringcolumn) FROM atable;
