Oracle Database Replication: Step-by-Step Guide + Tools

The exponential growth of data presents exciting opportunities for businesses to innovate, optimize, and personalize operations. However, ensuring the high availability of large volumes of data at any time plays a crucial role in leveraging its potential. Data replication can be an optimal solution to address this issue as it creates synchronized copies of your data across multiple systems. This implies that even if your system fails, another copy can seamlessly take over and minimize downtime and disruptions. 

Most businesses across industries trust Oracle, a well-established database software and technology company, to store their data in Oracle databases. This has enabled the company to develop the Oracle database replication feature to streamline the process. It enhances data availability, facilitates disaster recovery, and enables faster access to data, empowering businesses to unlock the full potential of their data and improve operational efficiency. This article provides a step-by-step guide to implementing the best tools for efficient Oracle database replication.

What is Database Replication?

Database replication refers to copying and synchronizing data from one source to another, typically across multiple databases or systems. This data duplication ensures that the same information is available in various databases. 

Database Replication can occur in real-time or on a scheduled basis, involving all or only a subset of the data from the source database. It also serves many purposes, including high availability, load balancing, data distribution, reporting, and analytics.

What is Oracle Database Replication?

Oracle database replication is a robust functionality developed by Oracle that enables you to create and maintain multiple target database copies in synchronization with the source database. Here, either your source or destination is an Oracle database. 

Oracle database replication supports two forms—basic and advanced. Basic replication provides read-only copies for faster local access, while advanced replication enables updates on synchronized copies across multiple databases.  

Oracle database replication also allows you to keep your data in sync in real-time across diverse locations, aggregate data from multiple branches, and share specific datasets with vendors. It empowers you to track the changes made to the source database and apply those updates to the replica databases. This guarantees data consistency across your entire database ecosystem.

Common Reasons for Oracle Database Replication

Disaster recovery

Critical business operations require minimal downtime. A synchronized replica at a different location ensures business continuity when the primary site faces hardware failure, natural disasters, or infrastructure issues.

Load distribution

Heavy read operations can overload a single database instance. Distributing read queries across multiple database copies optimizes performance while maintaining data consistency.

Reporting and analytics

Production databases shouldn't handle resource-intensive reporting queries. A separate reporting database copy prevents analytical workloads from impacting operational performance.

Data Migration

System upgrades and database migrations need minimal downtime. Real-time replication maintains synchronization between old and new systems during transition periods.

Development

Development teams need production-like data. Replication provides realistic test environments without risking production data integrity.

Types of Oracle Database Replication Methods

Synchronous replication

Data changes are committed simultaneously across all database copies. The primary database waits for confirmation from replica databases before completing transactions. This ensures exact data copies across all databases in real-time.

Pros

• Real-time consistency
• Automatic failover capability
• Best for financial transactions

Cons

• Higher transaction latency
• Network bandwidth intensive
• Performance impact on primary database

Asynchronous replication

Changes from the primary database are captured and queued for later transmission. Replicas apply changes with a time delay ranging from subseconds to minutes. The primary database doesn't wait for replica confirmation.

Pros

• Minimal impact on the primary database
• Better performance than synchronous
• Network interruption tolerant

Cons

• Potential data loss during failures
• Time lag in data consistency
• More complex conflict resolution
• Manual failover required

Snapshot replication

Creates point-in-time copies of database objects at scheduled intervals. Data is refreshed periodically rather than continuously. Ideal for data that doesn't require real-time updates.

Pros

• Low network bandwidth usage
• Simple to set up and maintain
• Good for reference data
• Minimal production impact

Cons

• Stale data between refreshes
• Resource intensive during refresh
• Not suitable for real-time needs
• Storage space overhead

Multi-master replication

All database copies can accept write operations. Changes made to any database are propagated to all other copies.

Pros

• High availability for writes
• Good for distributed teams
• Load balancing for all operations

Cons

• Higher maintenance overhead
• Requires more coordination
• Performance impact during conflicts

Materialized view replication

Creates read-only copies of data subsets using database views. It can include data aggregations and transformations. Refreshed based on defined schedules or on-demand.

Pros

• Efficient for subset replication
• Supports data transformations
• Reduced storage requirements
• Good for reporting needs

Cons

• Read-only copies
• Limited to view definitions
• Refresh overhead
• Not for real-time data

Top 3 Ways to Implement Oracle Database Replication

You can easily implement the Oracle database replication in the following three ways:

Method 1: Oracle Database Replication Using Airbyte

Airbyte is an ELT data integration solution that facilitates effortless data replication between various sources and destinations, including Oracle DB. Its versatile replication capabilities enable data to be transferred in batches according to schedules and on demand. 

With Airbyte, you can replicate data from any source to the Oracle database and vice-versa within minutes. For ease of explanation, the Oracle DB is configured as a destination connector on the Airbyte platform in the following steps.

Step 1: Log in to your Airbyte account. If you haven’t already created an account, sign up here.

Step 2: On the Airbyte dashboard, click the Sources from the left side of the navigation pane and search your source connector in the Search box.

Step 3: Once you choose the source connector, fill in the necessary details of the connector and click the Set up source button to complete the source connector configuration.

Step 4: To configure Oracle DB as your destination connector, click the Destinations present on the Airbyte dashboard.

Step 5: Type Oracle in the Search tab.

Step 6: Click on the Oracle connector, fill in the necessary information, and click the Set up destination button to complete the Oracle destination configuration. Now, Airbyte will begin to test your Oracle DB connection.

Step 7: Following a successful destination setup, click on Create a Connection to establish a connection between your source system and the Oracle database within Airbyte. 

Step 8: Select the source and destination connections that you have just created.

Step 9: Fill in the connect Connection name and Set up the Replication frequency as per your requirement. Select the Schedule type as Scheduled, Manual, or Cron. 

Step 10: Configure other necessary settings and click on Set up Connection to begin the transfer process. This will successfully sync your data from the source system to your Oracle database.

Suggested read: Understand the different replication modes Airbyte offers here.

Method 2: Oracle Database Replication Using Oracle GoldenGate

Oracle GoldenGate is one of the robust tools within the Oracle ecosystem that facilitates data replication between databases. Using this tool, you can move data efficiently across multiple homogeneous and heterogeneous systems in near-zero downtime. 

GoldenGate comprises components that work together to achieve its functionality. It allows you to extract data from source databases, apply the necessary transformations, and deliver transformed data to one or more databases. 

GoldenGate also offers various advantages, some of which include providing real-time support, synchronizing multiple target databases with up-to-date information, and performing inflight data transformations.

By leveraging Oracle GoldenGate, you can establish a reliable and efficient data replication process within your Oracle database environment. Let’s see how:

Step 1: Open SQL*Plus and type the following SQL query to log in to your database as a system user with the required privileges.

sys as sysdba

Run the following command to enable logging mode, archive log mode, and supplement log data.

shutdown
startup mount
alter database archivelog;
alter database open;
select log_mode from v$database;
alter database add supplemental log data(all) columns;
select SUPPLEMENTAL_LOG_DATA_ALL from v$database;
alter database force logging;
alter system switch logfile;
alter database add supplemental log data;

Step 2: Create a user and allocate privileges for GoldenGate on both the source and target databases.

create user username identified by ggate;
grant resource, dba, connect to ggate;

Step 3: Connect to the new user (ggate) and create a table using the following command.

connect ggate/ggate;
create table tablename(column1 data type,..);
insert into employee values(value1, value2,..);

Step 4: Install Oracle GoldenGate by following the steps mentioned here. Now, create a GoldenGate admin user on both source and target databases and give them permissions.

create user goldenuser identified by goldenuser;
Grant resource, dba, connect to goldenuser;

Step 5: Now, create a GoldenGate Tablespace. The Interpreter is used to configure the Oracle GoldenGate Replication as shown below: 

Use the following command to create a GoldenGate tablespace.

create tablespace ODRgoldengate
datafile 'goldengate.dbf'
size 100m
autoextend on;
alter user goldenuser default tablespace ODRgoldengate;

You need to use the Manager, Pump, and Extract processes on the Oracle GoldenGate source. These processes will help you capture changes in the source database, send them efficiently, and manage the overall replication process for near real-time data movement.  They are configured with the GoldenGate command-line interpreter ggsci.exe. 

Run the following command in the ggsci.exe.

edit params ./GLOBALS

Type the following command in the text file that opens after executing the above command.

GGSCHEMA goldenuser

Exit the ggsci.exe application. Open the command prompt in the folder where GoldenGate is installed, and run the command below:

exit
sqlplus / as sysdba
@role_setup.sql

This completes setting up the managers. The next step is extraction.

Step 6: Run the following command in ggsci.exe to start the extraction process.

edit params extract

Add the following parameters to the extract configuration file that opens after the execution of the previous command.

EXTRACT extract
USERID goldenuser, PASSWORD goldenuser
EXTTRAIL ./dirdat/ex
CHECKPOINTSECS 1
TABLE ggate.*;

Then, use the following command to add a data pump. This process acts as a buffering mechanism to address network latency issues that can arise during data replication.

edit params pumpora

Add the following parameters to the data pump configuration file that opens after the execution of the previous command.

EXTRACT pumpora
PASSTHRU
RMTHOST 192.168.104.34, MGRPORT 7809
RMTTRAIL ./dirdat/RT
CHECKPOINTSECS 1
TABLE ggate.*;

Now, create a local trail file for the extract process. Before starting the capture process, link the data pump to the extract process using the following command.

ADD EXTRACT extract, TRANLOG, BEGIN now
ADD EXTTRAIL ./dirdat/ex, EXTRACT extract
ADD EXTRACT pumpora, EXTTRAILSOURCE ./dirdat/ex
Add RMTTRAIL ./dirdat/rt, EXTRACT pumpora
START EXTRACT EXTRACT
START EXTRACT PUMPORA

Step 7:Configuring target.

Execute the following command to create a checkpoint for ggate.

add checkpointtable goldenuser.checkpointtable

Execute the following command to set up the replicate file.

edit params repora

Add the following parameters to the text file that opens after the execution of the above command.

REPLICAT repora
USERID user1, PASSWORD user1
DISCARDFILE ./dirdsc/replcat1.dsc, PURGE
ASSUMETARGETDEFS
MAP ggate.*, TARGET ggate.*;

Register the process on the target database using the following command.

add replicat repora, EXTTRAIL ./dirdat/rt, checkpointtable goldenuser.checkpointtable

Step 8: The final step in setting up Oracle GoldenGate Replication is adding data and committing changes to the target table by using the following command:

insert into test values(2,'Naomika');
commit;

Check the target server for data updates.

Limitations of the Oracle GoldenGate Approach

Below are some of the limitations associated with the Oracle GoldenGate:

• Configuring Oracle GoldenGate requires an expert Oracle administrator to ensure the proper setup. 
• The extraction process consumes significant memory due to the caching of uncommitted transactions and the utilization of intermediate buffers, potentially impacting the source database's performance.

Method 3: Oracle Database Replication Using a Trigger-Based Method 

The trigger-based method is a technique for replicating data between Oracle databases. It leverages Oracle's built-in stored procedures called triggers that act as automated mini-programs. These triggers are designed to execute in response to specific database actions like INSERT, UPDATE, or DELETE on a designated table. 

When such an operation occurs on the source table, the trigger captures the change and replicates it to the target database. It allows for the real-time synchronization of data across multiple databases.

The trigger-based method operates synchronously. This means the source database transaction won't commit until the triggers successfully execute and replicate the changes to the target database. However, this method may involve performance issues like increased processing load or network latency, which can be handled using Oracle multi-master replication as a source database. 

Limitations of Using Triggers

• Triggers may increase the performance overhead of the Oracle database by imposing an additional workload on it.
• Managing and debugging triggers can be difficult, making the troubleshooting and root cause analysis more challenging.   

Why Choose Airbyte?

While we’ve explored various methods for Oracle database replication, using the Airbyte method for data replication is straightforward. Its library of 350+ built-in connectors can help you automate data pipelines and provide flexibility to integrate data from multiple sources. 

Here are some more features of the Airbyte that can help you streamline your data movement process:

• User-friendly Interface: With a no-code, intuitive interface, you can easily extract and load data without any technical expertise. This further allows you to explore data quickly and derive valuable insights for better decision-making.‍
• Connector Development Kit: The CDK provides tools and resources for developing connectors independently, tailored to your specific needs.
• Change Data Capture: Airbyte's CDC feature helps you capture and replicate real-time changes in data from various sources. It allows you to stay updated with the most recent changes in the data sources without repeatedly performing complete data transfers.‍
• PyAirbyte: It is an open-source Python library that bridges the gap between the flexibility of custom Python scripts and the power of the data integration platform. With PyAirbyte, you can access most Airbyte connectors to extract data rather than building them from scratch.
  

Conclusion

Oracle Database Replication is crucial for organizations that require high availability, efficient data distribution, and disaster recovery. By creating and maintaining multiple copies of the data, Oracle replication minimizes the risk of data loss due to unforeseen events.    

This article provides step-by-step methods for implementing Oracle database replication and explains its importance and limitations. It also explains how Oracle database replication provides real-time support while ensuring better database performance, improved analytics, and report generation on crucial business insights. 

FAQs

Q. What is Oracle Database?

Oracle Database is a powerful, commercial relational database management system (RDBMS) for storing, managing, and retrieving large amounts of data.

Q. When to use Data replication?

Data replication is essential when high availability and distributed computing are crucial. It is advantageous for organizations that need near-zero downtime and uninterrupted data access.

Q. What are the top five Database replication tools?

The top five database replication tools are Airbyte, Fivetran, Qlik, Informatica, and IBM Informix.