Oracle GoldenGate Best Practices: Dual Apply

Introduction

Oracle GoldenGate provides a real-time, log-based change data capture and replication software platform that enables high volumes of transactional data to be moved between homogenous and heterogeneous platforms and databases, even bi-directionally, in sub-second speed, with no impact. With this technology, Oracle provides continuous availability and real-time data integration solutions to deliver real-time access to real-time information.

Main Article

This document describes how to setup and configure an environment to perform what we are calling “Dual Apply”.   Dual apply is a method where you can run the same batch jobs on the source and target system.   In some cases you may not want GoldenGate to replicate certain batch jobs, for example you have a batch job that does a mass update of a million records taking advantage of parallelism on the source system.  GoldenGate does not capture the original statement nor does it have any knowledge of the degree of parallelism used.   All GoldenGate will capture is the individual operations in the redo log files.  In some cases it is more efficient to run the same job on both the source and target systems.  Dual Apply is a method of using GoldenGate event markers to mark the start of a batch job, pass along that information to the target system, pause the replication on the target system at the same point as the source system and run the batch job on the target.  Once the job is finished on the source, that information is also pass along to the target and once the batch job is completed on the target, the apply process are then restarted.  Also, in order to avoid having the changes replicated from the source to the target a batch user is needed to be able to exclude the operations from the normal replication process.

This document touches briefly on many important and complex concepts and does not provide a detailed explanation of any one topic since the intent is to present the material in the most expedient manner. The goal is simply to help the reader become familiar enough with the product to successfully design and implement an Oracle GoldenGate environment. To that end, it is important to note that the activities of design, unit testing and integration testing which are crucial to a successful implementation have been intentionally left out of the guide.

The authors of this document are Steven George and Sourav Bhattacharya

The complete document can be found on the Oracle Support site as MOS Document ID: 1451675.1

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