[pgrouting-users] One variant of pgr_trsp does not give correct result

[Chee Chon Thum]

I have created a test database with sample data from the pgrouting manual 2.0.
Scripts to create the tables:

CREATE TABLE edge_table (
    id serial,
    dir character varying,
    source integer,
    target integer,
    cost double precision,
    reverse_cost double precision,
    x1 double precision,
    y1 double precision,
    x2 double precision,
    y2 double precision,
    the_geom geometry
);

INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  2,0,   2,1);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES (-1, 1,  2,1,   3,1);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES (-1, 1,  3,1,   4,1);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  2,1,   2,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1,-1,  3,1,   3,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  0,2,   1,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  1,2,   2,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  2,2,   3,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  3,2,   4,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  2,2,   2,3);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1,-1,  3,2,   3,3);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1,-1,  2,3,   3,3);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1,-1,  3,3,   4,3);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  2,3,   2,4);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  4,2,   4,3);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  4,1,   4,2);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  0.5,3.5,  1.999999999999,3.5);
INSERT INTO edge_table (cost,reverse_cost,x1,y1,x2,y2) VALUES ( 1, 1,  3.5,2.3,  3.5,4);

UPDATE edge_table SET the_geom = st_makeline(st_point(x1,y1),st_point(x2,y2)),
                      dir = CASE WHEN (cost>0 and reverse_cost>0) THEN 'B'   -- both ways
                                 WHEN (cost>0 and reverse_cost<0) THEN 'FT'  -- direction of the LINESSTRING
                                 WHEN (cost<0 and reverse_cost>0) THEN 'TF'  -- reverse direction of the LINESTRING
                                 ELSE '' END;                                -- unknown

SELECT pgr_createTopology('edge_table',0.001);


After the tables are created, I ran the following SQL to calculate the shortest path from node 1 to node 11:

SELECT seq, id1 AS node, id2 AS edge, cost
FROM pgr_trsp(
  'SELECT id, source, target, cost FROM edge_table',
  1, 11, false, false
);

This was the result:
0;-1;0;0


But, when I used the other variant of pgr_trsp() to calculate the shortest path from edge 1 (position 0) to edge 11 (position 1):

SELECT seq, id1 AS node, id2 AS edge, cost
FROM pgr_trsp(
  'SELECT id, source, target, cost FROM edge_table',
  1, 0, 11, 1, false, false
);

I got the correct result:
0;1;1;1
1;2;4;1
2;5;8;1
3;6;11;1
4;11;-1;0


My system is running on Windows 7 Professional SP1 64-bit. My PostgreSQL info:

SELECT version();
PostgreSQL 9.3.5, compiled by Visual C++ build 1600, 64-bit

SELECT postgis_full_version();
POSTGIS="2.1.4 r12966" GEOS="3.4.2-CAPI-1.8.2 r3924" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.11.0, released 2014/04/16" LIBXML="2.7.8" LIBJSON="UNKNOWN" RASTER

SELECT pgr_version();
(2.0.0,pgrouting-2.0.0,0,d6ed2cb,master,1.53.0)


Dunno if this is a bug, so I posted it to the mailing list and hopefully someone can take a look at this.
Thank you.
 		 	   		  
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