1. Get the outlines of the circles (ran very fast)
create table circle_outlines as
SELECT distinct ST_ExteriorRing(the_circle) AS the_geom FROM circle_list;
create index idx_geom_circle_outlines on circle_outlines using gist (the_geom);
select distinct geometrytype(the_geom) from circle_outlines ; -- LINESTRING
2. Combine the lines
3A. Check out the geom type created, if interested (should be GEOMETRYCOLLECTION)