Book Image

Oracle Goldengate 12c Implementers Guide

By : John P Jeffries
Book Image

Oracle Goldengate 12c Implementers Guide

By: John P Jeffries

Overview of this book

The book is aimed at Oracle database administrators, project managers, and solution architects who wish to extend their knowledge of GoldenGate. The reader is assumed to be familiar with Oracle databases. No knowledge of GoldenGate is required.
Table of Contents (16 chapters)
12
A. GGSCI Commands
13
B. GoldenGate Installed Components
14
C. Acronyms
15
Index

The GoldenGate instantiation

An initial load synchronizes the source and target databases, which is an important first step in data replication. Commonly known as instantiation, it extracts an entire copy of the source dataset, transforms it if necessary, and applies it to the target tables. Data replication can then continue from this point.

One of GoldenGate's many features is change synchronization that keeps track of ongoing transactional changes while the initial load is being applied. This feature is used extensively as part of the supported zero downtime migration functionality, and when configured, the change data capture and delivery concurrent process tracks the incremental changes, which are then reconciled with the results of the initial load.

So why is instantiation so important? To answer this question, consider an UPDATE statement. By its nature, the row to be updated must exist on the target table; otherwise, the transaction will fail. This is also true for DELETE operations...