Spatial Database使用时的一次debug(sdo_nn)

spatial 检索的时候

SELECT b1.b_id
FROM building b1,building b2
WHERE b2.b_ID=‘b3‘
    AND sdo_nn(b2.shape, b1.shape,
     ‘sdo_num_res=5‘, 0.5) = ‘TRUE‘;

出现这种错误：
ORA-13249: SDO_NN cannot be evaluated without using index
ORA-06512: at "MDSYS.MD", line 1723
ORA-06512: at "MDSYS.MDERR", line 17
ORA-06512: at "MDSYS.PRVT_IDX", line 9

解决方案：
SELECT b1.b_id
FROM building b1,building b2
WHERE b2.b_ID=‘b3‘
    AND sdo_nn(b1.shape, b2.shape,
     ‘sdo_num_res=5‘, 0.5) = ‘TRUE’;

因为oracle的sdo_nn()方法，第一个参数instance.geometry需要是已经存在数据的，而第二个参数是待检索的。如果两个参数颠倒，就会出现如上所示的错误。