Is there an efficient way to split a table of Multi/Linestrings that overlap() and touch() into unique Linestrings (note: creating edges using topology is going very...very...very slow).
Here is some sample data that I've been playing with...
CREATE TABLE multilines ( "id" SERIAL NOT NULL PRIMARY KEY, "name" char(1) NOT NULL, "the_geom" geometry NOT NULL);-- add data, 3 multilines, ONE of the 'B' geoms has an interior 'donut hole' multilinestringINSERT INTO multilines(name, the_geom) VALUES ( 'A', 'MULTILINESTRING((2 1,0 3),(0 3,2 3),(2 3,2 1))'::geometry ), ( 'B', 'MULTILINESTRING((0 0,4 0),(4 0,4 4),(4 4,0 4),(0 4,0 0),(1 1,2 1),(2 1,2 2),(2 2,1 2),(1 2,1 1))'::geometry ), ( 'B', 'MULTILINESTRING((-1 -1,-1 -2),(-1 -2,-2 -2),(-2 -2,-2 -1),(-2 -1,-1 -1))'::geometry );Since I don't have a node table of where the intersections are (and it seems intuitively inefficient to generate one) I was hoping to just do this without generating another table (which most people doing this type of query seem to be doing).
Notably...when I do something like 'ST_Linemerge(st_collect(the_geom))' ...I get 1 row showing ALL the merged lines (which isn't what I'd want - I definitely want to break the lines into separate Multi and/or Linestrings, and run a DISTINCT query just to return one of the_geoms).
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