Oracle CDC for Oracle Real-Time Replication

Change Data Capture (CDC) is a powerful technology that enables the identification and capture of changes in data as they occur. This method is crucial for maintaining up-to-date data in environments where timely information is critical. Oracle CDC, in particular, is a solution designed to efficiently capture and move data changes from Oracle databases to other systems in real-time. By using Oracle CDC, businesses can ensure that their data systems are synchronized, reducing latency and enabling faster decision-making processes.

For a more in-depth look at the fundamentals of Change Data Capture, please refer to our blog on the subject.

What is Oracle CDC?

Oracle Change Data Capture (CDC) is a technology bespoke to Oracle databases and data storage systems that allows users to track and capture changes made to data in an Oracle database. This is essential for data replication, data warehousing, and other scenarios where changes to data in one system must be reflected in other downstream data stores. Oracle CDC works by providing access to an authoritative record of changes such as inserts, updates, and deletes, and then applying these changes to a target system.

Oracle CDC is helpful because while some changes are easy to detect, like new data inserts, others are more likely to pass unnoticed. For example, if a row is deleted within Oracle, the only way to detect the missing row is to maintain a constant record of all rows and cross reference any updates against this self-managed record. Maintaining and checking such an authoritative record adds significant cost to operations related to the Oracle database, both in terms of storage and performance.

In short, Oracle CDC provides users with the ability to ensure that downstream platforms like data warehouses are always in sync with the source Oracle database. Synchronizing data warehouses with source databases depends on the ability to detect changes in the source, and Oracle CDC guarantees that any relevant changes are detected without needing to maintain a separate record of changes within the source.

Evolution of Oracle's CDC capabilities

Oracle's CDC capabilities have evolved significantly over the years, with each new version solving specific challenges that arise during data replication and data movement projects. Typically, these advances in technology bring enhancements in performance, reliability, and functionality. Below, we explore the two major versions of Oracle CDC.

Oracle CDC 12c

Oracle CDC 12c introduced several advancements over its nascent predecessors. The primary step forward involved the newly integrated Oracle Streams technology, which improved performance and overhead.

While the technical under-the-hood details extend beyond the scope of this article, the introduction of stream-driven CDC provided a more integrated approach to data capture, providing an efficient and easy-to-use solution. It allowed for real-time data capture and replication, which was crucial for businesses needing immediate access to updated information.

Oracle CDC 19c

With Oracle CDC 19c, Oracle took another leap forward in data capture technology. This version focused on enhancing scalability and robustness. It introduced features that made it easier to manage large volumes of data and complex replication environments.

Oracle 19c also improved the integration with cloud services, making it a suitable choice for hybrid cloud environments. The 19c version emphasized security and compliance, ensuring that data capture processes adhered to the latest industry standards.

3 Benefits of Oracle Change Data Capture

Implementing Oracle CDC offers several significant advantages for businesses. Here are three key benefits:

• Real-time data replication: One of the primary benefits of Oracle CDC is its ability to replicate data in real-time. This means that any changes made to the source Oracle database are immediately reflected in the target system. This is crucial for applications that require up-to-date information, such as real-time analytics, reporting, and operational dashboards.
• Optimized data processing: Oracle CDC optimizes data processing by capturing only the changes made to the data, rather than processing the entire dataset. This reduces the amount of data that needs to be transferred and processed, leading to faster and more efficient data operations. It also minimizes the load on the network and the systems involved in data replication.
• Making decisions based on real-time insights: With Oracle CDC, businesses can make decisions based on real-time data insights. By having access to the most current data, decision-makers can respond more quickly to changing conditions, identify trends and patterns as they emerge, and improve overall business agility. This capability is essential for maintaining a competitive edge in today's fast-paced business environment.

CDC methods for Oracle real-time replication

There are several methods available for implementing CDC with Oracle databases, each with its own set of advantages and use cases. These methods can be broadly categorized into non-log-based and log-based methods.

Non-log-based methods

Non-log-based methods do not rely on database logs to capture changes. Instead, they use other techniques and available information to identify and capture data changes, like columns within database tables and specialized database infrastructure.

• Timestamps: Using timestamps is a straightforward method for CDC. By adding a timestamp column to the database tables, changes can be tracked based on the timestamp values. This method is simple to implement and works well for smaller databases or less frequent updates.
• Triggers: Triggers are another non-log-based method for CDC. Triggers are database objects that execute automatically when specific events occur, such as inserts, updates, or deletes. By creating triggers on the relevant tables, changes can be captured and stored in a separate table or sent directly to a target system.

Log-based methods

Log-based methods leverage the database's transaction logs to capture changes. Users can depend upon Oracle’s transaction logs to detect when data-changing transactions occur. These methods are efficient and scalable, making them suitable for larger databases and high-frequency updates.

• Oracle GoldenGate: Oracle GoldenGate is a comprehensive log-based CDC solution that provides high-performance data replication and integration. It captures changes from the source Oracle database's redo logs and applies them to the target system in real-time. GoldenGate supports a wide range of use cases, including data migration, disaster recovery, and data integration.
• Oracle XStream: Oracle XStream is another log-based CDC tool that allows for the capture and delivery of database changes. It uses the same underlying technology as Oracle GoldenGate but is designed for more lightweight and flexible integration scenarios. XStream is ideal for applications that require real-time data streaming and integration with other systems.

How to set up Oracle as a source for CDC

Setting up an Oracle database as a source for Change Data Capture typically amounts to a three-step process. Here is a general overview of what is required:

1. Choose a CDC tool: The first step is to choose a CDC tool that meets your requirements. Consider factors such as the volume of data, the frequency of changes, the target systems, and any specific integration needs. Tools like Oracle GoldenGate and Oracle XStream are popular choices for log-based CDC, while triggers and timestamps can be used for non-log-based methods.
2. Install and set up the tool: Once you have chosen a CDC tool, the next step is to install and configure it. This typically involves setting up the necessary software on both the source Oracle database and the target system. Follow the tool's documentation for detailed installation and configuration instructions. Ensure that all necessary permissions and configurations are in place to allow the tool to capture and replicate data changes.
3. Establish connection to Oracle database: After the tool is installed and configured, you need to establish a connection to the Oracle database. This involves specifying the connection parameters, such as the database hostname, port, username, and password. The CDC tool will use this connection to access the database and capture changes. Ensure that the connection is secure and that any necessary encryption or authentication measures are in place.

Leverage CData Oracle CDC connections

CData solves data connectivity and movement challenges such as those present in cases involving Oracle CDC. CData’s emphasis on user-friendly and non-technical tools helps ensure that the process of establishing reliable Oracle CDC does not need to be difficult or time-consuming.

CData’s enterprise data replication and warehousing tool, CData Sync, provides built-in support for CDC across a wide range of popular databases and data sources, including Oracle CDC. Sync streamlines the process of establishing secure connections to your Oracle instance, enabling CDC, and ensuring that data changes are always captured during your data movement projects. is  a range of connectors that can simplify the process of setting up and managing Oracle CDC. These connectors provide seamless integration with various data platforms and applications, allowing you to leverage Oracle CDC for real-time data replication and integration.

To see how CData Sync can can help you implement Oracle CDC for real-time reliable data replication, you can get started with a free 30-day trial of Sync today.