It is possible to identify and successfully perform spatial selections near vertices and end points of a long line stored using SDO_Geometry and a geographic coordinate system; however, identifying or selecting near the midpoint of the line or far from the vertices returns no selection.
The Oracle SDO_FILTER function used with SDO_Geometry data uses the geodetic model of great circle distances. The geodatabase searches and identifies using the Cartesian path.
The great circle path and the Cartesian path between two points are not exactly the same. This difference becomes evident on lines that cover great distances. The spatial location of the line in the great circle path can be different enough from the Cartesian path location of the line to prevent your spatial selection or identify from returning any information about the line.