Oracle GoldenGate Best Practices: GoldenGate Capture from a DataGuard with Cascaded Redo Logs

 

Introduction

This paper provides guidance and examples for setting up downstream extraction from an Oracle DataGuard Standby system that has been configured with cascading redo logs. We outline how to configure the cascade log shipping from the standby to the mining database as well has how to configure the extract process on the mining server to fetch necessary data from the DataGuard standby system. Instantiation of target systems from an DataGuard standby has special considerations and will also be addressed in this document. This architecture configuration using redo cascade is the most decoupled solution that can still provide realtime characteristics of change data capture. The focus of the document is intended for Oracle Database Administrators (DBAs), and Oracle Developers with basic knowledge of Oracle GoldenGate and Oracle DataGuard. The document is intended to be a supplement to the existing series of documentation available from Oracle.

 

The following assumptions have been made during the writing of this document:

» The reader has basic knowledge of Oracle GoldenGate products and concepts

» Referencing Oracle GoldenGate Version 12.2 and above

» Referencing Oracle RDBMS Version 11.2.0.4 and above

» Referencing OS: All Oracle GoldenGate supported platforms for Oracle

Oracle GoldenGate is the market leading data integration tool, it provides data capture from transaction logs and delivery for homogeneous/heterogeneous databases, big data and messaging systems. A key strength of Oracle GoldenGate is that it provides a flexible, de-coupled architecture that can be used to implement virtually any replication scenario.

Main Article

This document will address how to configure Oracle GoldenGate to extract data from an ADG Standby by utilizing cascading redo log shipping and a downstream mining server. This document assumes that the user already has the following systems configured: 1) a source rdbms, 2) an ADG Standby for the source system and 3) a mining database.  This document will outline the steps to enable those environments to work together for implementing downstream extraction from an ADG Standby.

 

flow_drawing_downstream_stdby

 

Configure Cascading Redo Log Shipping

    • This is a data guard configuration option. There are steps that need to be done at the source, ADG standby and downstream mining databases.

Source RDBMS Setup

    • There are a few steps that have to be executed on the source to enable downstream extraction from an ADG Standby. Enabling supplemental logging, and registering the extract are the main steps that will need to be executed on the source. This source system, after this preliminary work is completed, should not be impacted by OGG.

ADG Standby Setup

    • This document will not cover the complete setup of an ADG Standby. This document assumes the ADG Standby already exists. However, in order for the redo logs to be shipped to the mining database server, cascade redo log shipping will need to be enabled from the ADG Standby.

Downstream Mining Server Setup

    • A majority of the work will be done at this server. The extract process needs to be configured and the database has to be configured to receive the cascading redo logs being shipped from the ADG Standby server. The downstream mining server RDBMS version can be different than the ADG Standby. It is only required to be the same version or higher. The mining server can be patched and not impact the source systems.

Instantiation Considerations

    • Instantiation has similar requirements whether it is done from the source system or the ADG Standby System. There are certain steps that users need to be aware of to get a consistent copy of data from the Standby that are slightly different. This paper will not cover to the extent of the Document 1276058.1 “Instantiation from an Oracle Source Database with Oracle GoldenGate 12c”. This paper will focus on the unique requirements of the ADG Standby Server.

Summary

The details of setting up this configuration can be found on Oracle Support, MOS article

Add Your Comment