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    Convert Single Geometry to Multi-part Geometry in Oracle Spatial
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    Implementation Of Travelling Salesman Problem
    Create Polygon From Bearings And Distances
    Function That Returns a Compass Point From a Whole Circle Bearing
    Playing around with Centroids by using different seed values
    GeoRaptor 4.x Update 2
    Simple Oracle C Sprintf or Java String.format
    Some Oriented Point Functions
    Extracting Inner Rings Changed Ordinate Ordering: A Trap For Players Who Don't Read Documentation!
    PLS-00306: wrong number or types of arguments in call to 'SDO_GEOMETRY'
    Converting Google Earth Formatted Longitude/Latitude points to decimal degrees
    Oracle Business Intelligence Warehousing and Analytics - Spatial Summit
    How far inside, is inside? Measuring actual distance.
    Noding and building a polygon from single, overlapping linestrings
    Analyzing Spatial Query Performance Improvements in Oracle Spatial and Graph 12c Through Cross-Vendor Comparison
    ST_VertexN / ST_PointN - Extracting a specific point from any geometry
    Convert Single Point stored in SDO_ORDINATES to SDO_POINT_TYPE
    Aggregate APPEND Islands and XOR polygons
    Circular Arcs in Geodetic Polygons
    Some SDO_GEOMETRY/DIMINFO handling functions
    Applying And Extending Oracle Spatial - Book Released
    Changing all DIMINFO sdo_tolerance values for all metadata records in one go.
    Building Polygons from Incomplete Linestrings using ST_PolygonBuilder
    Computing Cardinal Directions to nearby geometries
    Intersecting two aggregated polygon layers with SC4O
    Spatial and Oracle 12c
    Update Triggers and SDO_GEOMETRY Equality
    Duplicate Geometry data and Data Models
    CENTROID package update
    How to calculate cumulative length of a linestring
    Useful Package of Wrapper Functions for Sdo_Util.AffineTransforms
    Compute Location from known Lat/Long point using delta easting and northing in miles
    SDO_AGGR_SET_UNION
    Sorting SDO_GEOMETRY data using the ORDER BY clause of a SELECT statement
    Creating linestrings from points
    Rounding Coordinates or Ordinates in SDO_GEOMETRY
    Effects of Sdo_Geometry Ordinate Precision on Performance
    Effects of Sdo_Geometry Ordinate Precision on Storage
    The Spatial filtering of geometries: The effect of tolerances on relationships
    Application of Delaunay Triangulation and Inverse Distance Weighting (IDW) in Oracle for Soils Interpolation
    Selecting all SDO_GTYPE values for all tables/sdo_geometry columns in a schema
    CENTROID package - Tips for Use
    Announcing the Spatial Companion For Oracle (SC4O)
    Filtering Rings (Oracle Spatial)
    Splitting a polygon using one or more linestrings
    isValid, isSimple, Dimension and CoordDim methods for SDO_Geometry
    Line Merging or Collecting lines together: ST_LineMerger
    ST_DeleteVertex for Oracle SDO_Geometry based on Jaspa/JTS
    3D/4D and SRID aware Conversion functions for SDO_Geometry: WKT and EWKT
    Topological vs Non-Topological Simplification/Generalization of Aggregated Area Geometies in Oracle
    Filtering very short linestrings via bitmap function index
    CENTROID For Oracle
    Gridding a sdo_geometry line/polygon object (Oracle)
    Finding centre and radius of a circular geometry
    Constraining geometry type for sdo_geometry column in a table.
    CASE Statements and SDO_GEOMETRY
    The Power of Constraints and Indexes for Spatial Constraints: stopping duplicate points
    Replacement for SDO_GEOM.RELATE - ST_Relate based on JTS
    Changing Oracle Spatial Index Parameters on existing index
    Writing Excel Spreadsheets files from within the Oracle database using Java and PL/SQL
    Writing xSV (eg csv) files from within the Oracle database using Java and PL/SQL
    A simple spike finder for Spatial/Locator
    JTS Java class compilation for 11g and above
    Random Spatial Search Procedure
    Geometry Snapping using JTS in Oracle
    Exposing JTS's MinimumBoundingCircle functionality
    Exposing JTS's Densifier functionality
    Using JTS's Comparison Functions - HausdorffSimilarityMeasure & AreaSimilarityMeasure with SDO_GEOMETRY
    Free JTS-based Area/Length Functions
    Handy way of systematically fixing polygon geometries with 13349 and other errors
    Standalone CENTROID package now available for download
    Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 4 Processing Geodetic data
    Configurable Buffer: JTS and Oracle
    Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 3
    Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 2
    Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 1
    Building Lines into Polygons in Oracle Locator / Spatial
    Finding Intersection Points between Line and Polygon
    SDO2GeoJSON
    Free version of sdo_length
    Alternative to my SQL based GetNumRings function
    External Tables and SDO_Geometry data.
    layer_gtype keyword issue when indexing linear data on 11g
    String Tokenizer for Oracle
    Free Aggregate Method for Concatenating 2D Lines in Oracle Locator 10g
    Reducing 5 Vertex Polygon to Optimized Rectangle
    Square Buffer
    Converting decimal seconds to string
    SDO_GEOM.VALIDATE_GEOMETRY_WITH_CONTEXT - 13356 Issues
    Valid conversion unit values for Oracle sdo_geom.sdo_length()
    Removing Steps in Gridded Vector Data - SmoothGrid for Oracle
    Oracle Spatial DISJOINT search/filtering
    Creating SDO_Geometry from geometric data recorded in the columns of a table
    Concave Hull Geometries in Oracle 11gR2
    Projecting SDO_GEOM_METADATA DIMINFO XY ordinates
    Instantiating MDSYS.VERTEX_TYPE
    New PL/SQL Packages - Rotate oriented point
    GeoRaptor Development Team
    Fast Refreshing Materialized View Containing SDO_GEOMETRY and SDO_GEOM.SDO_AREA function
    Performance of PL/SQL Functions using SQL vs Pure Code
    Implementing the BEST VicGrid Projection in Oracle 10gR2
    Making Sdo Geometry Metadata Update Generic Code
    ORA-13011 errors when using SDO_GEOM.VALIDATE_LAYER_WITH_CONTEXT()
    Extract Polygons from Compound Polygon
    Detecting sdo_geometries with compound (3-point Arcs) segments
    GEOMETRY_COLUMNS for Oracle Spatial
    Convert GML to SDO_Geometry in Oracle 10gR2
    Spatial Sorting of Data via Morton Key
    Swapping Ordinates in an SDO_GEOMETRY object
    New To_3D Function
    Extend (Reduce/Contract/Skrink) Function for Oracle
    Loading and Processing GPX 1.1 files using Oracle XMLDB
    Loading Spatial Data from an external CSV file in Oracle
    Calling the Oracle Spatial shapefile loader from within the Oracle database itself
    Implementing SDO_VertexUpdate/ST_VertexUpdate for Oracle
    Implementing SDO_RemovePoint/ST_RemovePoint for Oracle
    Implementing SDO_AddPoint/ST_AddPoint for Oracle
    ESRI ArcSDE Exverted and Inverted Polygons and Oracle Spatial
    Funky Fix Ordinates By Formula
    Implementing a SetPoint/ST_SetPoint function in Oracle
    Implementing an ST_SnapToGrid (PostGIS) function for Oracle Spatial
    Generating random point data
    Implementing an Affine/ST_Affine function for Oracle Spatial
    Implementing a Scale/ST_Scale function for Oracle Spatial
    Implementing a Parallel/ST_Parallel function for linestring data for Oracle Spatial
    Implementing a Rotate/ST_Rotate function for Oracle Spatial
    Limiting table list returned when connecting to Oracle Database using ODBC
    ST_Azimuth for Oracle: AKA Cogo.Bearing
    Implementing a Translate/ST_Translate/Move function for Oracle Spatial
    Elem_Info_Array Processing: An alternative to SDO_UTIL.GetNumRings and querying SDO_ELEM_INFO itself
    Minumum Bounding Rectangle (MBR) Object Type for Oracle
    How to extract elements from the result of an sdo_intersection of two polygons.
    How to restart a database after failed parameter change
    Fixing failed spatial indexes after import using data pump
    generate_series: an Oracle implementation in light of SQL Design Patterns
    Multi-Centroid Shootout
    Oracle Spatial Centroid Shootout
    On the use of ROLLUP in Oracle SELECT statements
    Surrounding Parcels
    Spatial Pipelining
    Using Oracle's SDO_NN Operator - Some examples
    Converting distances and units of measure in Oracle Locator
    Split Sdo_Geometry Linestring at a known point
    Forcing an Sdo_Geometry object to contain only points, lines or areas
    Unpacking USER_SDO_GEOM_METADATA's DIMINFO structure using SQL
    Generating multi-points from single point records in Oracle Spatial
    Object Tables of Sdo_Geometry
    Oracle Locator vs Oracle Spatial: A Reflection on Oracle Licensing of the SDO_GEOM Package
    FAST REFRESHing of Oracle Materialized Views containing Sdo_Geometry columns
    Australian MGA/AMG Zone Calculation from geographic (longitude/latitude) data
    Loading Shapefiles (SHP) into Oracle Spatial
    Oracle Spatial Mapping and Map Rendering Performance Tips
    The significance of sdo_lb/sdo_ub in USER_SDO_GEOM_METDATA: Do I need it?
    Oracle Spatial Forum - Melbourne April 2007
    Layer_GTypes for spatial indexes
    Oracle's SQL/MM Compliant Types
    Tips and Tricks

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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Elem_Info_Array Processing: An alternative to SDO_UTIL.GetNumRings and querying SDO_ELEM_INFO itself

Sunday December 21 2008 at 08:48

This article is in two parts: 1) on SDO_UTIL.GetNumRings; 2) and an outline of a function to return the element info array in its normalised form.

1. SDO_UTIL.GETNUMRINGS

Oracle Spatial, well at release 10g, has an undocumented function in the SDO_UTIL package called GetNumRings.

FUNCTION GETNUMRINGS RETURNS NUMBER
 Argument Name                  Type                    In/Out Default?
 ------------------------------ ----------------------- ------ --------
 GEOM                           SDO_GEOMETRY            IN

This function takes a polygon geometry object and returns the number of rings that compose it. So, if I provide it a simple xD polygon, it will tell me how many rings (outer and inner) compose it. Here is an example:

select mdsys.sdo_util.getnumrings(SDO_GEOMETRY(2003,NULL,NULL,SDO_ELEM_INFO_ARRAY(1,1003,3),SDO_ORDINATE_ARRAY(1,1,10,10))) as ringcount
  from dual;

RINGCOUNT
----------
         1

1 rows selected

I had a quick look at this function and found that it does not handle compound rings.

select a.polytype,sdo_util.getnumrings(a.geom) as ringcount,a.geom.sdo_elem_info 
  from projpoly2d a;

POLYTYPE                                 RINGCOUNT              GEOM.SDO_ELEM_INFO
---------------------------------------- ---------------------- ----------------------------
VERTEXWITHHOLE                           2                      NUMBER(1,1003,1,77,2003,1)
VERTEXNOHOLE                             1                      NUMBER(1,1003,1)
VERTEXNOHOLE                             1                      NUMBER(1,1003,1)
COMPOUNDOUTERSHELL                       0                      NUMBER(1,1005,2,1,2,1,5,2,2)
VERTEXNOHOLE                             1                      NUMBER(1,1003,1)
VERTEXWITHARCNOHOLE                      0                      NUMBER(1,1005,2,1,2,1,5,2,2)
NORMALISEDRECTANGLENOHOLE                1                      NUMBER(1,1003,3)
CURVEPOLYWITHHOLE                        2                      NUMBER(1,1003,4,7,2003,4)

8 rows selected

If you are worried about this, try just using straight SQL.

select polytype,count(b.column_value) 
  from projpoly2d a,
       table(a.geom.sdo_elem_info) b
 where b.column_value in (1003,1005,2003,2005)
group by polytype, b.column_value;

POLYTYPE                                 COUNT(B.COLUMN_VALUE)
---------------------------------------- ----------------------
VERTEXNOHOLE                             3
COMPOUNDOUTERSHELL                       1
NORMALISEDRECTANGLENOHOLE                1
VERTEXWITHHOLE                           1
CURVEPOLYWITHHOLE                        1
VERTEXWITHHOLE                           1
CURVEPOLYWITHHOLE                        1
VERTEXWITHARCNOHOLE                      1

8 rows selected

Or, as I have not published in this article how to construct and populate the projpoly2d table, here is something more explicit you can try yourself:

select sdo_util.getnumrings(a.geom) as ringcount
  from (SELECT SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                            NULL,
                            NULL,
                            SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                               11,2005,2, 11,2,1, 15,2,2,
                                               21,1005,2, 21,2,1, 25,2,2),
                            SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                13,10, 10,2,  7,10, 10,13, 13,10,
                                              106,110, 110,101, 114,110, 110,114,106,110)) as geom
          FROM dual) a;

RINGCOUNT
---------------------- 
0

1 rows selected

Which is wrong. So, let’s try pure SQL:

select count(*) as ringcount
  from TABLE(SELECT SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                            NULL,
                            NULL,
                            SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                               11,2005,2, 11,2,1, 15,2,2,
                                               21,1005,2, 21,2,1, 25,2,2),
                            SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                13,10, 10,2,  7,10, 10,13, 13,10,
                                              106,110, 110,101, 114,110, 110,114,106,110)).sdo_elem_info
          FROM dual) a
 where a.column_value in (1003,1005,2003,2005);

RINGCOUNT
---------------------- 
3

1 rows selected

Which is correct.

The SQL examples above are simplified and will not produce a correct in all cases. The reason for this is that the predicate:

...
 where b.column_value in (1003,1005,2003,2005)
...

Does not discriminate between the ordinate offset, etype and interpretation triplet that is a standard entry for sdo_elem_info_array. So, if an ordinate offset was either 1003, 1005, 2003 or 2005 it would incorrectly add to the count of rings.

The way to correctly query the sdo_elem_info_array is via a SQL pivot as follows:

SELECT count(*) as ringcount
  FROM (SELECT e.id,
               e.etype,
               e.offset,
               e.interpretation
          FROM (SELECT trunc((rownum - 1) / 3,0) as id,
                       sum(case when mod(rownum,3) = 1 then sei.column_value else null end) as offset,
                       sum(case when mod(rownum,3) = 2 then sei.column_value else null end) as etype,
                       sum(case when mod(rownum,3) = 0 then sei.column_value else null end) as interpretation
                  FROM TABLE(SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                                          NULL,
                                          NULL,
                                          SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                                             11,2005,2, 11,2,1, 15,2,2,
                                                             21,1005,2, 21,2,1, 25,2,2),
                                          SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                              13,10, 10,2,  7,10, 10,13, 13,10,
                                                            106,110, 110,101, 114,110, 110,114,106,110)).sdo_elem_info
                            ) sei
                 GROUP BY trunc((rownum - 1) / 3,0)
                ) e
       ) i
 WHERE i.etype in (1003,1005,2003,2005);

RINGCOUNT
----------
         3

1 rows selected

To create your own function – in case you are worried about use of an undocumented Oracle function – using the above approach, is fairly trivial:

create or replace Function GetNumRings( p_geometry in mdsys.sdo_geometry ) 
  Return Number Deterministic
Is
  v_ring_count number := 0;
Begin
  SELECT count(*) as ringcount
    INTO v_ring_count
    FROM (SELECT e.id,
                 e.etype,
                 e.offset,
                 e.interpretation
            FROM (SELECT trunc((rownum - 1) / 3,0) as id,
                         sum(case when mod(rownum,3) = 1 then sei.column_value else null end) as offset,
                         sum(case when mod(rownum,3) = 2 then sei.column_value else null end) as etype,
                         sum(case when mod(rownum,3) = 0 then sei.column_value else null end) as interpretation
                    FROM TABLE(p_geometry.sdo_elem_info) sei
                   GROUP BY trunc((rownum - 1) / 3,0)
                  ) e
         ) i
   WHERE i.etype in (1003,1005,2003,2005);
  Return v_ring_count;
End GetNumRings;
/ 
SHOW ERRORS

And, testing it:

SELECT GetNumRings(NULL) As RingCount FROM DUAL;

RINGCOUNT
----------------------
0

1 rows selected

SELECT GetNumRings(SDO_GEOMETRY(2001,NULL,SDO_POINT_TYPE(10,10,10),NULL,NULL)) As RingCount FROM DUAL;

RINGCOUNT
----------------------
0

1 rows selected

SELECT GetNumRings(SDO_GEOMETRY(2002,NULL,NULL,SDO_ELEM_INFO_ARRAY(1,2,1),SDO_ORDINATE_ARRAY(1,1,10,10))) As RingCount FROM DUAL;

RINGCOUNT
----------------------
0

1 rows selected

SELECT GetNumRings(SDO_GEOMETRY(2003,NULL,NULL,SDO_ELEM_INFO_ARRAY(1,1003,3),SDO_ORDINATE_ARRAY(1,1,10,10))) As RingCount FROM DUAL;

RINGCOUNT
----------------------
1

1 rows selected

SELECT GetNumRings(SDO_GEOMETRY(2003,NULL,NULL,SDO_ELEM_INFO_ARRAY(1,1003,3,5,2003,3),SDO_ORDINATE_ARRAY(1,1,100,100,20,20,40,40))) As RingCount FROM DUAL;

RINGCOUNT
----------------------
2

1 rows selected

SELECT GetNumRings(SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                                NULL,
                                NULL,
                                SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                                   11,2005,2, 11,2,1, 15,2,2,
                                                   21,1005,2, 21,2,1, 25,2,2),
                                SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                    13,10, 10,2,  7,10, 10,13, 13,10,
                                                   106,110, 110,101, 114,110, 110,114,106,110)
                               )
                   )
        as RingCount
  FROM DUAL;

RINGCOUNT
----------------------
3

1 rows selected

Note that the function did not need EXCEPTION handling for NULL or non-polygon geometries as the answer returned from the SQL is correct.

2. Function Returning Normalised Element Info Array

The Oracle sdo_geometry ordinates and element info arrays are simple, one dimensional (denormalised) arrays that, for the newcomer is, strangly, a little daunting. But we can approach them more easily. Oracle 10g has the SDO_UTIL.GetNumVertices function that returns a more natrual MDSYS.Vertex_Type (see documentation). But there are not many functions that present the elements of the sdo_elem_info_array in a normalised form.

To do so, we will need to write a function that can be used in a query. I prefer PIPELINE functions in this case as they are more efficient on memory use and are more “native” to the way the Oracle database itself works.

Let’s start with a traditional coding to access the SDO_ELEM_INFO_ARRAY varray.

First we need to create an appropriate data types:

create or replace type t_ElemInfoType As Object (
   offset           NUMBER,
   etype            NUMBER,
   interpretation   NUMBER);

create or replace type T_ElemInfoSetType as Table of T_ElemInfoType;

Now we can code a function, in the traditional way, that returns many (a set) of t_ElemInfoTypes.

Create Or Replace Function GetElemInfo(
  p_geometry in mdsys.sdo_geometry)
  Return T_ElemInfoSetType pipelined
Is
  v_elements  number;
Begin
  If ( p_geometry is not null ) Then
    If ( p_geometry.sdo_elem_info is not null) Then
      v_elements := ( ( p_geometry.sdo_elem_info.COUNT / 3 ) - 1 );
      <<element_extraction>>
      for v_i IN 0 .. v_elements LOOP
         PIPE ROW ( T_ElemInfoType(
                    p_geometry.sdo_elem_info(v_i * 3 + 1),
                    p_geometry.sdo_elem_info(v_i * 3 + 2),
                    p_geometry.sdo_elem_info(v_i * 3 + 3) ) );
      end loop element_extraction;
    End If;
  End If;
  Return;
End GetElemInfo;

Which we can use as follows:

SELECT e.*
  FROM TABLE(GetElemInfo(SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                                      NULL,
                                      NULL,
                                      SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                                         11,2005,2, 11,2,1, 15,2,2,
                                                         21,1005,2, 21,2,1, 25,2,2),
                                      SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                          13,10, 10,2,  7,10, 10,13, 13,10,
                                                         106,110, 110,101, 114,110, 110,114,106,110)
                                     )
                         ) 
            ) e;

OFFSET                 ETYPE                  INTERPRETATION
---------------------- ---------------------- ----------------------
1                      1005                   2
1                      2                      1
5                      2                      2
11                     2005                   2
11                     2                      1
15                     2                      2
21                     1005                   2
21                     2                      1
25                     2                      2

9 rows selected

Now, let’s re-write the function using the SQL approach we introduced in part 1.

Create Or Replace Function GetElemInfo(
  p_geometry in mdsys.sdo_geometry)
  Return T_ElemInfoSetType pipelined
Is
  v_elements  number;
  CURSOR c_elements( p_geometry in mdsys.sdo_geometry) Is
  SELECT e.id,
         e.etype,
         e.offset,
         e.interpretation
    FROM (SELECT trunc((rownum - 1) / 3,0) as id,
                 sum(case when mod(rownum,3) = 1 then sei.column_value else null end) as offset,
                 sum(case when mod(rownum,3) = 2 then sei.column_value else null end) as etype,
                 sum(case when mod(rownum,3) = 0 then sei.column_value else null end) as interpretation
            FROM TABLE(p_geometry.sdo_elem_info) sei
           GROUP BY trunc((rownum - 1) / 3,0)
          ) e;
Begin
  If ( p_geometry is not null ) Then
    If ( p_geometry.sdo_elem_info is not null) Then
    <<element_extraction>>
    for rec IN c_elements(p_geometry) LOOP
       PIPE ROW ( T_ElemInfoType(
                    rec.offset,
                    rec.etype,
                    rec.interpretation ) );
      end loop element_extraction;
    End If;
  End If;
  Return;
End GetElemInfo;

Again, testing:

SELECT e.*
  FROM TABLE(GetElemInfo(SDO_GEOMETRY(2007,  -- two-dimensional multi-part polygon with hole 
                                      NULL,
                                      NULL,
                                      SDO_ELEM_INFO_ARRAY(1,1005,2, 1,2,1, 5,2,2,
                                                         11,2005,2, 11,2,1, 15,2,2,
                                                         21,1005,2, 21,2,1, 25,2,2),
                                      SDO_ORDINATE_ARRAY(  6,10, 10,1, 14,10, 10,14,  6,10,
                                                          13,10, 10,2,  7,10, 10,13, 13,10,
                                                         106,110, 110,101, 114,110, 110,114,106,110)
                                     )
                         ) 
            ) e;

OFFSET                 ETYPE                  INTERPRETATION
---------------------- ---------------------- ----------------------
1                      1005                   2
1                      2                      1
5                      2                      2
11                     2005                   2
11                     2                      1
15                     2                      2
21                     1005                   2
21                     2                      1
25                     2                      2

9 rows selected

Note they are identical which shows that there are many ways to code an algorithm in PL/SQL. I personally prefer an SQL approach but others prefer a programmatic approach. One day I will compare the two (as in the above) using Tom Kyte’s RUNSTATS package and the PL/SQL PROFILER.

Till then, I hope this article is of use to someone out there.

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Comment [3]

one word: Holy Macaroni Batman!!!
awesome article. thank-you thank-you.
How can I be the man when uda man?!?

— John Donaldson · 20 March 2011, 17:12 · #

John,

Thank you for you praise. It is great to be appreciated.

One day, udabe the man.

Simon

Simon Greener · 21 July 2011, 02:22 · #

I was looking for away to detect compound line strings (Elem_info 1,4,x) and found your functions.
As I am interested in the first three values of the elem_info_array I found that the PLSQL approach returns the elem info in the order as they appear in the collection. The SQL approach does not.

— Rene Westenberg · 3 September 2013, 12:01 · #