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

Replicating data with materialized views

Materialized view based replication is very useful when the changes at the master site do not have to be immediately available at the secondary sites. This is also useful when the connectivity between the master and slave sites is not continuous. When only a subset of tables or portions of the tables are required at the secondary sites in an asynchronous fashion, materialized view based replication is one of the most common ways to achieve it.

As we discussed in the previous chapter, a materialized view is a replica of a table that can be refreshed at regular intervals or on demand. During a refresh, only the final values of the changed rows are pulled down, no matter how many updates were applied to the master table. This results in the reduced amount of data being transferred to the remote site.

Let's use the LAND_PARCELS table in our example to show the replication process using the materialized views. First, the database administrators at the city...