Oracle Spatial Extension of the RDBMS Oracle by spatial data types and operations –introduced in version 8 (current version is 10G Release 2) is based on the object relational extensions of Oracle –user defined data types and object classes is possible –Fields may also contain objects and nested tables (Non-First Normal Form, NF 2 ) –Object classes may be augmented by methods –Support of class hierarchies (incl. inheritance) –besides normal relations also ‘object tables‘ can be defined Spatial data type is realised by the object class SDO_GEOMETRY and its methods

Oracle Spatial Features of Oracle Spatial 10G (I) Representation of 0-2 dimensional geometric and topological primitives, complexes, and aggregates Coordinate values can have 2-4 dimensions Representation of 3D objects is possible –allerdings keine Konzepte für Volumina enthalten: keine 3D-Topologie; keine dreidimensionalen Funktionen und Operatoren –pragmatisches Vorgehen: Speicherung der Boundary Representation eines 3D-Objekts als Flächenaggregat mit 3D-Koordinatenwerten Geometric and topological functions (only for 2D coordinates) –among others: Egenhofer-relations and 2D CSG operations Spatial indexing using R-Trees (2D-4D) and Quadtrees (2D) –especially important for spatial joins

Oracle Spatial Features of Oracle Spatial 10G (II) Coordinate Reference Systems (CRS) within the DB –geodetic and projective CRS –linear referencing systems (e.g. for street networks or hydrography) –methods for coordinate transformations are included within the DB Graph algorithms for network analyses (shortest paths, maximum flows) Functions for spatial analysis –clustering Geocoding of spatial data –e.g. association of addresses and coordinates Representation of regular grids of (nearly) arbitrary size (GeoRaster) –each raster cell can hold a n-dimensional vector of values –GeoRaster are georeferenced –efficient access methods (e.g. retrieval of a specific rectangular area)

Oracle Spatial Spatial Datatype in Oracle: SDO_GEOMETRY Object class, that is defined within the Oracle user accound MDSYS –Access or referencing: MDSYS.SDO_GEOMETRY Attributes of class SDO_GEOMETRY: SDO_GTYPENUMBER –Geometry type (e.g = Polygon with two-dimensional coordinates) SDO_SRIDNUMBER –Identifier (ID) of the spatial reference system within the DB SDO_POINTMDSYS.SDO_POINT_TYPE –Point geometry SDO_ELEM_INFOMDSYS.SDO_ELEM_INFO_ARRAY –Structure and interpretation of the coordinate list SDO_ORDINATESMDSYS.SDO_ORDINATE_ARRAY –List of coordinates (cf. ‘Spaghetti‘ representation)

Oracle Spatial Example for a Table with a Spatial Attribute CREATE TABLE TabWithGeometry ( ID NUMBER(8), DESCRIPTION VARCHAR2(30), GEOMETRY MDSYS.SDO_GEOMETRY); IDDESCRIPTIONGEOMETRY 1A simple point 2A polygon with a hole

Oracle Spatial Geometry Types All geometries may have 2-4D coordinates Polygons can have holes Besides, there also exist aggregates, in which geometries of the same type or of mixed type can be contained, e.g.: –MultiPoint –MultiPolygon –MultiGeometry

Oracle Spatial Geometry Metadata Any column of type SDO_GEOMETRY must be explicitly registered within the DBMS –Ensures automatic updating of spatial indices –Naming of coordinate axes and restriction of value domains –Definition of a tolerance value for spatial queries and operations System tables for the storage and query of geometry metadata –USER_SDO_GEOM_METADATA Metadata for all spatial attributes of the current user –ALL_SDO_GEOM_METADATA Metadata for all spatial attributes of the whole database (of all user accounts) with read permission for the current user –DBA_SDO_GEOM_METADATA Metadata for all spatial attributes of the whole database (of all user accounts); only accessible by database administrators

Oracle Spatial USER_SDO_GEOM_METADATA For any column of type SDO_GEOMETRY a row has to be inserted into USER_SDO_GEOM_METADATA. Attributes: TABLE_NAMEVARCHAR2(32) –Name of the table containing the column of type SDO_GEOMETRY COLUMN_NAMEVARCHAR2(32) –Name of the column containing the SDO_GEOMETRY DIMINFOMDSYS.SDO_DIM_ARRAY –Identifier, extent, and tolerance of each dimension. Here, objects from the class MDSYS.SDO_DIM_ARRAY have to be specified. SRIDNUMBER –ID of the spatial reference system (foreign key referring to the system table MDSYS.CS_SRS). If unknown or undefined, enter NULL value.

Oracle Spatial SDO_DIM_ARRAY SDO_DIM_ARRAY consists of one SDO_DIM_ELEMENT per dimension of the coordinate values of the geometry Structure of SDO_DIM_ELEMENT: SDO_DIMNAMEVARCHAR2(64) –Identifier (name) of the dimension; e.g. ‘easting‘ or ‘latitude‘ SDO_LBNUMBER –Minimum coordinate value of that dimension SDO_UBNUMBER –Maximum coordinate value of that dimension SDO_TOLERANCENUMBER –minimal distance up to which two coordinate values are considered as being equal

Oracle Spatial Continuation of the Example: Creation of Metadata INSERT INTO USER_SDO_GEOM_METADATA (TABLE_NAME, COLUMN_NAME, DIMINFO, SRID) VALUES(‘TabWithGeometry‘, ‘Geometry‘, MDSYS.SDO_DIM_ARRAY( MDSYS.SDO_DIM_ELEMENT(‘X‘, , 180.0, ), MDSYS.SDO_DIM_ELEMENT(‘Y‘, -90.0, 90.0, ) ), null );

Oracle Spatial Insertion of Spatial Data (I) INSERT INTO TabWithGeometry VALUES (1, ‘A simple point‘, MDSYS.SDO_GEOMETRY(2001, NULL, MDSYS.SDO_POINT_TYPE(10,11,NULL), NULL, NULL) ); inserts a tuple with a point object at coordinates (10,11) into the table. SDO_GTYPE Spatial refe- rence system SDO_ELEM_INFO SDO_ORDINATES

Oracle Spatial Insertion of Spatial Data (II) INSERT INTO TabWithGeometry VALUES (1, ‘A simple point‘, MDSYS.SDO_GEOMETRY(‘POINT(10 11)‘) ); inserts a tuple with a point object at coordinates (10,11) into the table. Same example as before, but for the specification of the geometry object the Well-Known-Text format (WKT) is used (cf. lecture 8, slide 16) Point in the Well-Known-Text format Constructor of the class SDO_GEOMETRY creates from Well-Known-Text geometries corresponding Oracle Spatial geometries

Oracle Spatial Insertion of Spatial Data (III) INSERT INTO TabWithGeometry VALUES (2, ‘A polygon‘, MDSYS.SDO_GEOMETRY(2003, NULL, NULL, MDSYS.SDO_ELEM_INFO(1,1003,1), MDSYS.SDO_ORDINATES(9,9, 12,9, 12,10, 9,10, 9,9) ) ); inserts a tuple with a polygon into the table. SDO_GTYPE: Polygon Spatial refe- rence system 5 coordinate pairs define the closed ring; the last pair has to match the first pair 1st coordinate starts at 1st position; outer ring; straight line segments It is not a simple point!

Oracle Spatial Insertion of Spatial Data (IV) INSERT INTO TabWithGeometry VALUES (3, ‘Polygon with hole‘, MDSYS.SDO_GEOMETRY(2003, NULL, NULL, MDSYS.SDO_ELEM_INFO(1,1003,1, 11,2003,1), MDSYS.SDO_ORDINATES(9,9, 12,9, 12,10, 9,10, 9,9, 10,10, 10.5,10.5, 11,10, 10,10) ) ); inserts a polygon (rectangle) with (triangular) hole into the table. SDO_GTYPE: Polygon Spatial refe- rence system The first 5 coordinate pairs define the outer ring; the following 4 the inner ring 1st coordinate starts at 1st position; outer ring; straight line segments It is not a simple point! 1st coordinate begins at 11th position; inner ring; straight line segments