How to solve “Error creating GEOS Coordinate Sequence” in Postgis?

Question

When I run this query:

TRUNCATE sertaozinho.apps;

INSERT INTO sertaozinho.apps (id,tipo,the_geom)
VALUES (DEFAULT, 'app' ,(
    SELECT st_union(
    CASE 
    WHEN area.cobertura = 'lago' THEN ST_Transform(st_buffer(area.the_geom,15), 32723)
    WHEN area.cobertura = 'rio' THEN ST_Transform(st_buffer(area.the_geom,100) , 32723)
    WHEN linhas.name = 'corrego' THEN ST_Transform(st_buffer(linhas.the_geom,30) , 32723)
    WHEN pontos.tipo = 'nascente' THEN ST_Transform(st_buffer(pontos.the_geom,50) , 32723)
    END )
    FROM sertaozinho.area, sertaozinho.linhas, sertaozinho.pontos
    )
    )

I get this output:

ERROR: Error creating GEOS Coordinate Sequence
Estado de SQL:XX000

The query is only a sequence of buffers and then an union. The dataset contains about 1000 polygons and 200 lines. I have already succeeded in running this query, but after some minor edits in the polygons it stopped working. Any clue? EDIT: Sometimes after this query the server stops and needs to be restarted.

Answer 1

I'm guessing the problem is with the CASE statement, since it doesn't have an explicit ELSE component, so returns NULL. This is completely untested, but try inserting one line:

...
WHEN pontos.tipo = 'nascente' THEN ST_Transform(st_buffer(pontos.the_geom,50) , 32723)
ELSE 'POLYGON EMPTY'::geometry
END )
...

Note: you should always show your version with SELECT PostGIS_Full_Version();