Sdo_nn is not showing desired results

Question

Hello,
We have the following query :
SELECT p.codigo_proveedor_ca, p.descripcion AS Proveedor, DECODE(p.habitual,0,'N','S') AS HAB, DECODE(p.h_24,0,'N','S') H24,
     b.codigo_base, b.tipo_via || ' ' || b.nom_via || ',' || b.numero_via || ' ' || B.PISO AS DIRECCION_PROV, b.codigo_pais,
b.codigo_provincia, b.codigo_ine, b.codigo_zona, mg.numero AS NUMERO_GEN, b.localidad, ROUND(MDSYS.SDO_NN_DISTANCE(1),0) AS DISTANCIA,
b.GIS_X, b.GIS_Y, b.GIS_NIVEL_XY, b.GIS_GEO_OK, b.GIS_TIPO_SRIDENUM
FROM SAT_BASES_PROVEEDORES b,
     SAT_BASE_PROVEEDOR_MEDIOS_GEN mg,
     SAT_PROVEEDORES_CA p
WHERE b.codigo_pais = 'ESP' AND b.activo = 1
AND mg.codigo_proveedor_ca = b.codigo_proveedor_ca AND mg.codigo_base = b.codigo_base
     -- Medio Genérico 'TAXI'
     AND mg.codigo_medio_generico = '2' AND mg.activo = 1 AND P.ACTIVO = 1
     AND p.codigo_proveedor_ca = b.codigo_proveedor_ca
     -- Coordinates of GRANOLLERS
     AND SDO_NN(b.GEOMETRIA,MDSYS.SDO_Geometry(2001, 1000000,MDSYS.SDO_Point_type(188161,5043776,NULL),NULL, NULL) ,
     'SDO_BATCH_SIZE = 25', 1 ) = 'TRUE'
ORDER BY DISTANCIA;
What we want is to get the providers which are near to a given town. To get this we are using SDO_NN function and also
SDO_NN_DISTANCE to calculate the distance to the given coordinates.
Our problem is that there are two providers with the same coordinates that should be shown in the query result but one of them is not shown and we don't understand why.
If we use SDO_NUM_RES instead of SDO_BATCH_SIZE the provider is shown, but as far as I know, if you use this parameter not all the WHERE clauses are evaluated. Am I wrong?
What are we doing wrong?
Thanks in advance,
Eva.

Answer 1

Are you on Oracle 9i? In 9i, I have never been able to get this query to work successfully this way. I had to rewrite it to use a in-line view and a rownum and make some other changes. I think it is buggy, as are many of the 9i spatial objects (full of horrid memory leaks etc.)
I have been able to hack around the fact that it cannot find the nearest neighbor on it's own, by using an inline view in this way, but it has holes, I am sure:
Select DISTANCE, (list all your other selections) from
SELECT /*+ordered*/ SDO_NN_DISTANCE(1) DISTANCE, p.codigo_proveedor_ca, p.descripcion AS Proveedor, DECODE(p.habitual,0,'N','S') AS HAB, DECODE(p.h_24,0,'N','S') H24,
b.codigo_base, b.tipo_via || ' ' || b.nom_via || ',' || b.numero_via || ' ' || B.PISO AS DIRECCION_PROV, b.codigo_pais,
b.codigo_provincia, b.codigo_ine, b.codigo_zona, mg.numero AS NUMERO_GEN, b.localidad, ROUND(MDSYS.SDO_NN_DISTANCE(1),0) AS DISTANCIA,
b.GIS_X, b.GIS_Y, b.GIS_NIVEL_XY, b.GIS_GEO_OK, b.GIS_TIPO_SRIDENUM
FROM SAT_BASES_PROVEEDORES b,
SAT_BASE_PROVEEDOR_MEDIOS_GEN mg,
SAT_PROVEEDORES_CA p
WHERE b.codigo_pais = 'ESP' AND b.activo = 1
AND mg.codigo_proveedor_ca = b.codigo_proveedor_ca AND mg.codigo_base = b.codigo_base
-- Medio Genérico 'TAXI'
AND mg.codigo_medio_generico = '2' AND mg.activo = 1 AND P.ACTIVO = 1
AND p.codigo_proveedor_ca = b.codigo_proveedor_ca
-- Coordinates of GRANOLLERS
AND SDO_NN(b.GEOMETRIA,MDSYS.SDO_Geometry(2001, 1000000,MDSYS.SDO_Point_type(188161,5043776,NULL),NULL, NULL) ,
'SDO_BATCH_SIZE = 25', 1 ) = 'TRUE'
AND ROWNUM < 1000
ORDER BY DISTANCE
WHERE ROWNUM < 2';
This should give you the closest result. If you want the closest 2, you would set that in the last line. I had to mess around with the rownum < 1000 line in my query. It appears that the order by distance has no affect. If I set it to ROWNUM < 50, often times, the closest 2 items weren't in the inner select elements. So they weren't available in the outer results.
I also found this issue very frustrating. I actually had a hard time believeing it was so junky, until I proved it was the problem with this statement. Please let us know if it solves your issue also.