Trying to use Oracle Locator for latitude and longitude proximity searches

Question

I am prototyping using Oracle Locator to do proximity searches and other spatial operations within the database in our software products. I’ve got it working fine in SQL Server, where geodetic is built in as well as geometric features, but with Oracle we’re trying to restrict ourselves to the Locator features so our customers are forced to buy the add-on. I am getting perplexing results, as you can see if you run the little test program I wrote.
I am using lat and long as the point coordinates. I am inserting the data using
SDO_GEOMETRY(2001, 4326, SDO_POINT_TYPE(?, ?, null), null, null
Then I am doing the search with
SELECT pointname, SDO_NN_DISTANCE (1) distance_in_miles
FROM geotest g
WHERE SDO_NN(g.geopoint, sdo_geometry(2001, 4326, SDO_POINT_TYPE(38.683, 123.083, NULL), NULL, NULL), 'distance=1000 unit=mile', 1) = 'TRUE'
ORDER BY distance_in_miles
I am getting distances from 56 to 86 units, whatever the units are.
Am I attempting the impossible with Locator, to use lat and long and then expect the sdo_nn function to work in miles?
Select results:
POINTNAME DISTANCE_IN_MILES
Point number 19 56.8497254738894
Point number 17 57.0758802885512
Point number 5 62.096857977487
Point number 3 67.3555572959989
Point number 16 70.8005407529483
Point number 1 73.0370426667902
Point number 9 73.1047740624495
Point number 14 73.1451566004902
Point number 11 74.9344307572887
Point number 10 75.3710529989389
Point number 2 75.423714095366
Point number 8 77.2121183101138
Point number 4 77.6458963754559
Point number 18 80.4569749046142
Point number 6 81.0025026191188
Point number 20 81.8444977200089
Point number 13 83.4095236051998
Point number 15 86.9333533902019
Point number 7 88.9312783958262
Point number 12 98.72957787982
Point number 0 98.9999489634554
21 rows selected

Answer 1

Couple of things that we found out using sdo_nn here...
It works...but the knobs need to be turned in the right order...
You may have done this already...but here is what we have...
a. we create our table containing the location sdo_geometry column ..( in our case the column is called location )
b.We loaded the data..If you elected to use a partitioned table for your spatial data and created the corresponding spatial index as local...your sql will need to account for that.if your index is global ..don't worry about it
c. We inserted the metadata...this needs to be done once per table...by either the dba or the schema owner...
INSERT INTO USER_SDO_GEOM_METADATA (TABLE_NAME, COLUMN_NAME, DIMINFO, SRID)
VALUES ('<YOUR TABLE NAME>', '<SPATIAL COLUMN NAME>',
MDSYS.SDO_DIM_ARRAY
(MDSYS.SDO_DIM_ELEMENT('LONGITUDE', -180.0, 180.0, 0.5),
MDSYS.SDO_DIM_ELEMENT('LATITUDE', -90.0, 90.0, 0.5)
8307);
COMMIT;
If this is not done before the spatial index is created...stuff won't work...
d. create your spatial index
e. our query looked something like this...( I changed the table names )
This returns the top 30 results sorted by distance in feet...
SELECT LOCATION_KEY,
result_center_distance
FROM
SELECT LOCATION_KEY,
SDO_NN_DISTANCE(1) result_center_distance
FROM LOCATION_OWNER.D_LOCATION dlocation
WHERE SDO_NN(dlocation.LOCATION,
MDSYS.SDO_GEOMETRY(2001,8307,MDSYS.SDO_POINT_TYPE(-97.07845,33.138006,null),null,null), 'SDO_NUM_RES=31 unit=FOOT distance=5800.0 SDO_MAX_MEMORY=50000000', 1) = 'TRUE'
ORDER BY 2
WHERE ROWNUM <= 31
We had to use this structure because our index is local...and sdo_nn will return the sdo_num_res results for each partition...so you need to get the results first..then treat it as a top-n query...
If you index is global...this should work
SELECT LOCATION_KEY,
SDO_NN_DISTANCE(1) result_center_distance
FROM LOCATION_OWNER.D_LOCATION dlocation
WHERE SDO_NN(dlocation.LOCATION,
MDSYS.SDO_GEOMETRY(2001,8307,MDSYS.SDO_POINT_TYPE(-97.07845,33.138006,null),null,null), 'SDO_NUM_RES=31 unit=FOOT distance=5800.0 SDO_MAX_MEMORY=50000000', 1) = 'TRUE'
ORDER BY 2
If you want the distance in MILE...replace FOOT by MILE...
good luck...
Edited by: user5431290 on Oct 23, 2011 9:36 AM