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
About the Authors
About the Reviewers
Table Comparing Simple Feature Access/SQL and SQL/MM–Spatial

Storage resolution versus resolution used by functions

When data is collected from external data sources, it is very important to understand different accuracy and storage characteristics of the data. Coordinates of the geometry are stored in VARRAYS of numbers in Oracle Spatial. The Number data type in the Oracle database stores fixed and floating-point numbers. Numbers of virtually any magnitude can be stored, with up to 38 digits of precision. This means() that any coordinate in the Oracle Spatial format can have up to 38 digits in decimal representation. This level of precision is not usually required for many applications, so it is important to understand how the number of digits used for each coordinate affects the storage and performance of the spatial applications.

Precision and accuracy

Oracle Spatial also has the concept of tolerance for geometry data. As described in Chapter 1, Defining a Data Model for Spatial Data Storage, tolerance is used to distinguish unique coordinates in...