Sdo_geom.validate_geometry_with_context - Reporting multiple errors

Question

All Oracle versions.
sdo_geom.validate_geometry_with_context appears to report only the first error it finds in an sdo_geometry.
Thus, it reports only the first duplicate vertex in "ORA-13356: adjacent points in a geometry are redundant", or only
the first loop in a ring for "ORA-13349: polygon boundary crosses itself".
I understand that, for some errors, reporting more than one error would be difficult but for more simple errors such as
the two mentioned, it would be most helpful to have validate_geometry_with_context report more than one error location
in its return string. Such reporting would reduce the time and effort required in find-fix-find error correction cycle.
Comments?
regards
Simon

Answer 1

A triangle is a bad example for ORA-13349. In fact, it is impossible for a triangle not to be right unless two points are the same.
I don't agree with a lot of the comments because I know that many simple types of errors can be detected. Here is
a polygon with a hole that has multiple 13349 errors because of "bow-ties" or "loops in the outer boundary".
select sdo_geom.validate_geometry_with_context(MDSYS.SDO_GEOMETRY(2003, NULL, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,1,17,2003,1),
                                  MDSYS.SDO_ORDINATE_ARRAY(
                                  523960.5, 5201847.7, 525174.7, 5202361.9, 525171.4, 5202328.8, 524843.0, 5202839.7,
                                  524889.4, 5202833.0, 523748.1, 5202484.7, 523781.3, 5202554.4, 523960.5, 5201847.7,
                                  524141.2, 5202192.9, 524223.1, 5202550.3, 524197.1, 5202520.5, 524502.3, 5202546.6,
                                  524584.2, 5202293.4, 524614.0, 5202345.6, 524171.0, 5202189.2, 524141.2, 5202192.9)),0.005) as error
          from dual;
ERROR                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
13349 [Element <1>] [Ring <1>][Edge <5>][Edge <7>] As you can see, validate_geometry_with_context() only returns the first loop in the outer boundary (1003).
But with a slight modification of approach we can get at least one more:
select sdo_geom.validate_geometry_with_context(b.geom,0.005) as error
from (select mdsys.sdo_util.extract(
                MDSYS.SDO_GEOMETRY(2003, NULL, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,1,17,2003,1),
                                   MDSYS.SDO_ORDINATE_ARRAY(
                                   523960.5, 5201847.7, 525174.7, 5202361.9, 525171.4, 5202328.8, 524843.0, 5202839.7,
                                   524889.4, 5202833.0, 523748.1, 5202484.7, 523781.3, 5202554.4, 523960.5, 5201847.7,
                                   524141.2, 5202192.9, 524223.1, 5202550.3, 524197.1, 5202520.5, 524502.3, 5202546.6,
                                   524584.2, 5202293.4, 524614.0, 5202345.6, 524171.0, 5202189.2, 524141.2, 5202192.9)),1,a.elem_no) as geom
         from (select level as elem_no from dual connect by level < 3) a
      ) b;
ERROR
13349 [Element <1>] [Ring <1>][Edge <5>][Edge <7>]
13349 [Element <1>] [Ring <1>][Edge <7>][Edge <5>]So, by extension, it is possible to return all the other bow-ties: I have done this in a function I have written. I now
need to extend it to find all other bow-ties in a ring.
I have function that finds all duplicate vertices (13356) in a geometry. Works well.
select rownum as point, b.valid, c.geometry
  from (select substr(sdo_geom.validate_geometry_with_context(a.geom,0.005),1,40) as valid,
               a.geom
          from (select MDSYS.SDO_GEOMETRY(2006, NULL, NULL,
                                  MDSYS.SDO_ELEM_INFO_ARRAY(1,2,1,13,2,1),
                                  MDSYS.SDO_ORDINATE_ARRAY(50.0, 15.0, 55.0, 15.0, 55.0, 15.0, 55.0, 15.0, 60.0, 15.0, 60.0, 15.0, 65.0, 15.0)) as geom
                  from dual) a
        ) b,
        TABLE(sdo_error.getErrors(b.geom,0.005)) c;
POINT VALID                                    GEOMETRY
1     13356 [Element <1>] [Coordinate <2>] MDSYS.SDO_GEOMETRY(2001,NULL,MDSYS.SDO_POINT_TYPE(55,15,NULL),NULL,NULL)
2     13356 [Element <1>] [Coordinate <2>] MDSYS.SDO_GEOMETRY(2001,NULL,MDSYS.SDO_POINT_TYPE(55,15,NULL),NULL,NULL)
3     13356 [Element <1>] [Coordinate <2>] MDSYS.SDO_GEOMETRY(2001,NULL,MDSYS.SDO_POINT_TYPE(60,15,NULL),NULL,NULL)As I said, this can be done for simple elemental errors. Errors that involve interactions of rings for example are harder. But, gee, other
software packages provide such capability so it is possible. And, these are data-level issues so I think it reasonable that Oracle
provides an improved set of functions and not hand it over to external GIS software clients.
regards
Simon