Thursday September 01 2011 at 09:28
One often processes sdo_geometry data looking for errors with SQL we get errors in the SQL that stop us seeing what the result is.
select count(*)
from oracle_test_geometries a
where a.geometry is not null;
COUNT(*)

70
select substr(sdo_geom.validate_geometry(a.geometry,0.005),1,10) as errCode
from oracle_test_geometries a
where a.geometry is not null
group by substr(sdo_geom.validate_geometry(A.geometry,0.005),1,10);
Error starting at line 1 in command:
select substr(sdo_geom.validate_geometry(a.geometry,0.005),1,10) as errCode
from oracle_test_geometries a
group by substr(sdo_geom.validate_geometry(A.geometry,0.005),1,10)
Error report:
SQL Error: ORA06502: PL/SQL: numeric or value error
ORA06512: at "MDSYS.SDO_GEOM", line 125
ORA06512: at "MDSYS.SDO_GEOM", line 460
06502. 00000  "PL/SQL: numeric or value error%s"
*Cause:
*Action:
So, how do we find out what is in error? The following bit of anonymous PL/SQL is helpful in this situation.
set serveroutput on size unlimited
DECLARE
v_err varchar2(10);
BEGIN
FOR rec IN (SELECT id, geometry FROM ORACLE_TEST_GEOMETRIES) loop
BEGIN
v_err := substr(SDO_GEOM.VALIDATE_GEOMETRY(rec.geometry,0.5),1,10);
If ( v_err <> 'TRUE' ) Then
dbms_output.put_line('Geometry with ID  '  rec.id  '  validate result is '  v_err );
End If;
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line('Geometry with ID  '  rec.id  '  failed to validate with '  SQLCODE );
END;
END LOOP;
END;
/
anonymous block completed
Geometry with ID  204  validate result is 13350
Geometry with ID  205  validate result is 13356
Geometry with ID  28  validate result is 13366
Geometry with ID  141  validate result is 13356
Geometry with ID  25  validate result is 13351
Geometry with ID  29  validate result is 13349
Geometry with ID  30  validate result is 13349
Geometry with ID  37  validate result is 13341
Geometry with ID  45  validate result is NULL
Geometry with ID  46  validate result is 13028
Geometry with ID  47  validate result is 13356
Geometry with ID  48  validate result is 13356
Geometry with ID  49  validate result is 13356
Geometry with ID  50  validate result is 13351
Geometry with ID  51  validate result is 13351
Geometry with ID  52  validate result is 13351
Geometry with ID  53  failed to validate with 6502
Geometry with ID  54  validate result is 13028
Geometry with ID  55  validate result is 13028
Geometry with ID  56  validate result is 13031
Geometry with ID  57  validate result is 13032
Geometry with ID  58  validate result is 13033
Geometry with ID  59  validate result is 13034
Geometry with ID  61  validate result is 13371
Geometry with ID  62  validate result is 13354
Geometry with ID  63  validate result is 13341
Geometry with ID  64  validate result is 13342
Geometry with ID  65  validate result is 13343
Geometry with ID  66  validate result is 13348
Geometry with ID  67  validate result is 13346
Geometry with ID  201  validate result is 13356
Geometry with ID  202  validate result is 13348
Geometry with ID  203  validate result is 13366
Note the line:
Geometry with ID – 53 – failed to validate with 6502
The geometry associated with it is:
select geometry
from oracle_test_geometries a
where a.id = 53;
GEOMETRY

MDSYS.SDO_GEOMETRY(NULL,NULL,NULL,NULL,NULL)
Which, patently, blows up validate_geometry(), though it shouldn’t. Because this geometry stopped the original SQL SELECT statement, we must exclude it if our nonPL/SQL SELECT statements are to succeed. One can do so by nominating the id as above:
where a.id = 53
Or one could do this:
where a.geometry is not null
and a.geometry.sdo_gtype is not null;
Now, what if we tried to fix all the geometries in one non PL/SQL based UPDATE statement:
update oracle_test_geometries a
set a.geometry = sdo_util.rectify_geometry(a.geometry,0.005)
where a.geometry is not null
and a.geometry.sdo_gtype is not null;
Error starting at line 1 in command:
update oracle_test_geometries a
set a.geometry = sdo_util.rectify_geometry(a.geometry,0.005)
where a.geometry is not null
and a.geometry.sdo_gtype is not null
Error report:
SQL Error: ORA13199: the given geometry cannot be rectified
ORA06512: at "MDSYS.MD", line 1723
ORA06512: at "MDSYS.MDERR", line 17
ORA06512: at "MDSYS.SDO_UTIL", line 716
13199. 00000  "%s"
*Cause: This is an internal error.
*Action: Contact Oracle Support Services.
Is it really that bad (ie contact Oracle Support Services)? Maybe. But before you do you need to know which of the many geometries in the table caused:
SQL Error: ORA13199: the given geometry cannot be rectified
OK, we can fix many of the errors by constructing PL/SQL targeted at fixing specific errors. What follows can be used to fix 13349 (bowtie in outer boundary of polygon) and 13356 (duplicate vertices):
set serveroutput on size unlimited
DECLARE
v_id oracle_test_geometries.id%type;
CURSOR c_geometries_to_fix Is
select id
from oracle_test_geometries a
where a.geometry is not null
and a.geometry.sdo_gtype is not null
and SDO_GEOM.VALIDATE_GEOMETRY(a.geometry,0.5) IN ('13349','13356')
for update of geometry;
BEGIN
OPEN c_geometries_to_fix;
LOOP
FETCH c_geometries_to_fix INTO v_id;
EXIT WHEN c_geometries_to_fix%NOTFOUND;
BEGIN
UPDATE oracle_test_geometries a
SET a.geometry = sdo_util.rectify_geometry(a.geometry,0.005)
WHERE CURRENT OF c_geometries_to_fix;
dbms_output.put_line('RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id '  v_id);
EXCEPTION
WHEN OTHERS THEN
BEGIN
UPDATE oracle_test_geometries a
SET a.geometry = sdo_geom.sdo_union(a.geometry,a.geometry,0.005)
WHERE CURRENT OF c_geometries_to_fix;
dbms_output.put_line('SDO_UNION was successful for oracle_test_geometries geometry with id '  v_id);
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line('Could not rectify oracle_test_geometries geometry with id '  v_id);
END;
END;
END LOOP;
CLOSE c_geometries_to_fix;
COMMIT;
END;
/
show errors
anonymous block completed
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 29
SDO_UNION was successful for oracle_test_geometries geometry with id 30
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 47
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 48
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 49
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 141
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 201
RECTIFY_GEOMETRY was successful for oracle_test_geometries geometry with id 205
NOTE: You have to have Spatial to execute the SDO_UNION unless you use the one in my GEOPROCESS package.
Of course, what is needed are a set of functions/techniques for fixing other errors,
My TOOLS package includes procedures that can be used to check daily updates and attempt to fix them:
/*** function GeometryCheck
** description Procedure that processes the supplied object looking
** for errors and correcting where possible.
** Writes activity to FEATURE_ERRORS table.
** param p_schema The owner of the table/geometry column data.
** param p_tableName The table holding the geometry data to be checked.
** param p_ColumnName The sdo_geometry column in the table to be checked.
** param p_whereClause A predicate to limit the activity to specific rows.
**/
Procedure GeometryCheck( p_schema IN VarChar2,
p_tableName IN VarChar2,
p_ColumnName IN VarChar2,
p_whereClause IN VarChar2);
I hope this is helpful to someone.
Comments?

Comment [5]
I’ve never understood why rectify_geometry doesnt do ‘what it says on the tin’ for all spatial errors.
I’ve been fixing the various errors i’ve come across by running sdo_union inside rectify_geometry – not sure whether this is smart or stupid.
— Thomas · 1 September 2011, 11:23 · #
Thomas,
I concur about rectify_geometry given the documentation does say:
The only problem of putting one function inside the other is that if the inside one fails then the whole collection fails.
So, one should not put rectify_geometry inside sdo_union because it just may fail as shown above.
Also, for those out there who are nonSpatial users, my GEOPROCESS.GeoUnion function could be substituted for sdo_union.
regards
Simon
— Simon Greener · 1 September 2011, 23:33 · #
How to know the bad geometries in a POLYGON Spatial feature table of count 5000000
— venu · 20 December 2011, 06:09 · #
You could do this:
select mdsys.sdo_geom.validate_geometry(a.<your sdo_geometry colummn name>,0.005) as valid_code,
count(*)
from <Your Table> a
group by mdsys.sdo_geom.validate_geometry(a.<your sdo_geometry colummn name>,0.005);
regards
Simon
— Simon Greener · 20 December 2011, 06:50 · #
Simon,
A useful addition to your GeometryCheck procedure would be to include a parameter for a size delta. In other words, if the area or length is within 0.5% of the original, make the change. Otherwise, leave it alone for a carbon based unit to review.
Bryan
— Bryan Hall · 11 January 2013, 19:06 · #