Book Image

Oracle 11g Streams Implementer's Guide

Book Image

Oracle 11g Streams Implementer's Guide

Overview of this book

From smaller businesses through to huge enterprises ñ users all over the world often require access to data 24 hours a day. Distributed database systems proliferate the world of data sharing providing an ability to access real-time data anywhere, anytime. Oracle Streams, a built-in feature of the Oracle database, is a data replication and integration feature critical to the success and wellbeing of enterprises in today's fast moving economy. This book provides the reader with solid techniques to master Oracle Streams technology and successfully deploy distributed database systems. This book quickly goes over the basics and gets you up and running with a simple Oracle 11g Streams environment. It will serve as an excellent companion to the Oracle Streams Administration Guide. It is intended for Oracle database architects and administrators, and provides in-depth discussion on must-know information for the design, implementation, and maintenance of an Oracle Streams environment. The book does not attempt to regurgitate all the information in the Oracle Streams Administration Guides, but rather provides additional clarification and explanation of design, implementation, and troubleshooting concepts that are often elusive in Streams documentation. It also identifies helpful tools and Oracle resources to add to your knowledge base, as well as tried and tested tricks and tips to help you tame Oracle Streams. The book starts by introducing and explaining the components of Oracle Streams and how they work together. It then moves on logically, helping you to determine your distributed environment requirements and design your Streams implementation to meet those requirements. Once these concepts are discussed, the book moves to configuration and basic implementation examples to help solidify those concepts. It then addresses advanced features such as tags, down-stream capture, and conflict resolution. You then move on to maintenance techniques such as documenting the environment, effectively planning and implementing changes to the environment, and monitoring and troubleshooting the environment. When you have studied the techniques and completed the hands-on examples, you will have an understanding of Oracle Streams' core concepts and functionally that will allow you to successfully design, implement, and maintain an Oracle Streamed environment.
Table of Contents (14 chapters)
Oracle 11g Streams Implementer's Guide
Credits
About the Authors
About the Reviewers
Preface

Conflict resolution


Conflict between User 1 and User 2 has happened. Unbeknown to both of them, they have both inserted the exact same row of data to the same table, at roughly the same time. User 1's insert is to the STRM1 database. User 2's insert is to the STRM2 database.

Normally the transaction that arrives second will raise an error. It is most likely that the error will be some sort of primary key violation and that the transaction will fail. We do not want that to happen. We want the transaction that arrives last to "win" and be committed to the database.

At this point, you may be wondering "How do I choose which conflict resolution to use?" Well, you do not get to choose, the Business Community that you support will determine the rules most of the time. They will tell you how they want conflict resolution handled. Your responsibility is to know what can be solved with built-in conflict resolutions and when you will need to create custom conflict resolution.

Going back to User 1...