SDO_NN - Nearest neighbour geometry based on condition

Question

Hi All,
I have two spatial tables SPL_ROADS and SPL_VILLAGES which stores the road and village information respectively. There are 4 categories of roads – NH, SH, MDR and VR. These are stored in same table (SPL_ROAD). Now I need a query to get nearest NH, nearest SH, nearest MDR and nearest VR and distance for selected villages or for all the villages.
I am using below query to get nearest road for all the villages.
SELECT /*+ LEADING(sv) */
sv.name, sr.name, trunc(SDO_NN_DISTANCE(1),2) dist
FROM spl_roads sr,
spl_villages sv
WHERE
SDO_NN(sr.geom, sv.geom,'sdo_num_res=1 unit=KM', 1) = 'TRUE'
But if I query for nearest NH using below query, it returns null.
SELECT /*+ LEADING(sv) */
sv.name, sr.name, trunc(SDO_NN_DISTANCE(1),2) dist
FROM spl_roads sr,
spl_villages sv
WHERE sr.category = 'NH'
SDO_NN(sr.geom, sv.geom,'sdo_num_res=1 unit=KM', 1) = 'TRUE' ORDER BY 1;
Please suggest me to get nearest road based on categories. I am expecting results in below format.
ROAD_ID | NAME | Nearest NH | distance from NH| Nearest SH | distance from SH | Nearest MDR |distance from MDR| Nearest VR| distance from VR
Thanks,
Sujnan

Answer 1

Hi,
Yes. The query takes very long time. I have written PL/SQL function to do this. Here I have to return multiple values from function. For this I have created user type called VILL_NN_ROAD_OBJ. The function will return this user type.
Here is user type and pl/sql function script.
CREATE OR REPLACE TYPE VILL_NN_ROAD_OBJ is object (
nh_road_id varchar2(50),
nh_dist number(10,2),
nh_road_name varchar2(250),
nh_road_num varchar2(50),
sh_road_id varchar2(50),
sh_dist number(10,2),
sh_road_name varchar2(250),
sh_road_num varchar2(50),
mdr_road_id varchar2(50),
mdr_dist number(10,2),
mdr_road_name varchar2(250),
mdr_road_num varchar2(50),
odr_road_id varchar2(50),
odr_dist number(10,2),
odr_road_name varchar2(250),
odr_road_num varchar2(50)
REATE OR REPLACE FUNCTION WEBRISNEW.GETNNROAD(inGeom SDO_GEOMETRY, in_year_id VARCHAR2) RETURN VILL_NN_ROAD_OBJ
IS
nnobj VILL_NN_ROAD_OBJ;
--nntab VILL_NN_ROAD_TAB;
BEGIN
nnobj:=VILL_NN_ROAD_OBJ(null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null);
SELECT /*+ INDEX(a SPL_ROAD_TEMP_GEOM_IDX) */
rd.kpwd_road_id, rd.kpwd_road_name, rd.kpwd_road_num, SDO_NN_DISTANCE(1) INTO
nnobj.nh_road_id, nnobj.nh_road_name, nnobj.nh_road_num, nnobj.nh_dist
FROM spl_roads sr inner join road_link_year_assoc rlya on sr.mslink = rlya.mslink
inner join kpwd_ns_road_details rd on rd.kpwd_road_id = rlya.kpwd_road_id and
rd.year_id = rlya.year_id and rlya.year_id=in_year_id and
rd.kpwd_road_category=1
WHERE SDO_NN(sr.geom, inGeom, 'sdo_batch_size=10 unit=km',1)='TRUE'
and ROWNUM <2;
SELECT /*+ INDEX(a SPL_ROAD_TEMP_GEOM_IDX) */
rd.kpwd_road_id, rd.kpwd_road_name, rd.kpwd_road_num, SDO_NN_DISTANCE(1) INTO
nnobj.sh_road_id, nnobj.sh_road_name, nnobj.sh_road_num, nnobj.sh_dist
FROM spl_roads sr inner join road_link_year_assoc rlya on sr.mslink = rlya.mslink
inner join kpwd_ns_road_details rd on rd.kpwd_road_id = rlya.kpwd_road_id and
rd.year_id = rlya.year_id and rlya.year_id=in_year_id and
rd.kpwd_road_category=2
WHERE SDO_NN(sr.geom, inGeom, 'sdo_batch_size=10 unit=km',1)='TRUE'
and ROWNUM <2;
SELECT /*+ INDEX(a SPL_ROAD_TEMP_GEOM_IDX) */
rd.kpwd_road_id, rd.kpwd_road_name, rd.kpwd_road_num, SDO_NN_DISTANCE(1) INTO
nnobj.mdr_road_id, nnobj.mdr_road_name, nnobj.mdr_road_num, nnobj.mdr_dist
FROM spl_roads sr inner join road_link_year_assoc rlya on sr.mslink = rlya.mslink
inner join kpwd_ns_road_details rd on rd.kpwd_road_id = rlya.kpwd_road_id and
rd.year_id = rlya.year_id and rlya.year_id=in_year_id and
rd.kpwd_road_category=2
WHERE SDO_NN(sr.geom, inGeom, 'sdo_batch_size=10 unit=km',1)='TRUE'
and ROWNUM <2;
SELECT /*+ INDEX(a SPL_ROAD_TEMP_GEOM_IDX) */
rd.kpwd_road_id, rd.kpwd_road_name, rd.kpwd_road_num, SDO_NN_DISTANCE(1) INTO
nnobj.odr_road_id, nnobj.odr_road_name, nnobj.odr_road_num, nnobj.odr_dist
FROM spl_roads sr inner join road_link_year_assoc rlya on sr.mslink = rlya.mslink
inner join kpwd_ns_road_details rd on rd.kpwd_road_id = rlya.kpwd_road_id and
rd.year_id = rlya.year_id and rlya.year_id=in_year_id and
rd.kpwd_road_category=2
WHERE SDO_NN(sr.geom, inGeom, 'sdo_batch_size=10 unit=km',1)='TRUE'
and ROWNUM <2;
-- dbms_output.put_line(dist || '--' || local_gid);
--insert into temp_vill_roads(vill_mslink, road_name)
--values (local_gid, item.mslink);
-- nntab:=VILL_NN_ROAD_TAB(nnobj);
return nnobj;
END;
Here queries inside function selects nearest road of different road categories and distance from and village.
select getnnroad(geom, '1999-2000') from spl_major_villages where rownum<3
If I run above query I get below results.
GETNNROAD(GEOM,'1999-2000')
(BJP3, 59.24, NH218 Bijapur Hubli Road, NH218, AFZ1, 166.67, SH22 Gulbarga Hosur upto State Border Road, SH22, AFZ1, 166.67, SH22 Gulbarga Hosur upto State Border Road, SH22, ATN1, 2.46, SH12 Jevaragi Chikkodi Sankeshwar Road, SH12)
(HUK1, 62.84, NH4 Madras Bangalore Poona Road (Bangalore Section), NH4, AFZ1, 195.44, SH22 Gulbarga Hosur upto State Border Road, SH22, AFZ1, 195.44, SH22 Gulbarga Hosur upto State Border Road, SH22, AFZ1, 194.54, SH22 Gulbarga Hosur upto State Border Road, SH22)
But I need these values as individual columns. I can run below query to do this but I think it is not efficient method.
select getnnroad(geom, '1999-2000').NH_ROAD_ID, getnnroad(geom, '1999-2000').NH_ROAD_NAME,
getnnroad(geom, '1999-2000').NH_ROAD_NUM from spl_major_villages where rownum<3
If I run below query, it says invalid identifier.
select t.NH_ROAD_ID from (
select getnnroad(geom, '1999-2000') t from spl_major_villages where rownum<3)
Please suggest me an efficient solution to do this.
Thanks,
Sujnan