Book Image

Applying and Extending Oracle Spatial

By : Siva Ravada, Simon Greener
Book Image

Applying and Extending Oracle Spatial

By: Siva Ravada, Simon Greener

Overview of this book

Spatial applications should be developed in the same way that users develop other database applications: by starting with an integrated data model in which the SDO_GEOMETRY objects are just another attribute describing entities and by using as many of the database features as possible for managing the data. If a task can be done using a database feature like replication, then it should be done using the standard replication technology instead of inventing a new procedure for replicating spatial data. Sometimes solving a business problem using a PL/SQL function can be more powerful, accessible, and easier to use than trying to use external software. Because Oracle Spatial's offerings are standards compliant, this book shows you how Oracle Spatial technology can be used to build cross-vendor database solutions. Applying and Extending Oracle Spatial shows you the clever things that can be done not just with Oracle Spatial on its own, but in combination with other database technologies. This is a great resource book that will convince you to purchase other Oracle technology books on non-spatial specialist technologies because you will finally see that "spatial is not special: it is a small, fun, and clever part of a much larger whole".
Table of Contents (20 chapters)
Applying and Extending Oracle Spatial
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Table Comparing Simple Feature Access/SQL and SQL/MM–Spatial
Index

Understanding and using SDO_ORDINATES


When creating new spatial processing functions, sometimes only the SDO_GEOMETRY's array of ordinates (SDO_ORDINATES) need be processed. Two functions will be created that use two different methods for processing the ordinates. These functions are drawn from real-life situations that will be described.

Two things need to be understood about the SDO_ORDINATES attribute of the SDO_GEOMETRY object.

Firstly, the name of the SDO_GEOMETRY attribute that stores ordinate data is called SDO_ORDINATES, which is different from the underlying data type, which is called SDO_ORDINATE_ARRAY. This is the same as in a database table; an attribute may be called GID, but its data type Integer SDO_ORDINATE_ARRAY is defined as follows:

Create Or Replace  SDO_ORDINATE_ARRAY
    As VARRAY (1048576) Of Number;

Note

A VARRAY is a variable array.

The 1048576 ordinate limit can be removed at 11gR2 via execution of the sdoupggeom.sql script. See "A.3 Increasing the Size of Ordinate Arrays...