Change Data Capture

Change Data Capture (CDC) is a technology used to capture changes made to a database in real-time. CDC captures insert, update, and delete operations made to the database, and stores them in a separate log or file. CDC can be used to replicate data between databases, synchronize data between applications, and enable real-time data analysis.

For zero-downtime or near to zero downtime, it's important to have CDC technology. The databases having ACID properties ideally have inbuilt CDC technology to replicate changes to replicas. while others require the use of third-party tools or custom scripts.

What are ACID Databases?

ACID databases are databases that are designed to ensure that database transactions are processed reliably and consistently. ACID databases are characterised by their ability to provide the following guarantees:

Atomicity: Atomicity guarantees that a database transaction is processed as a single, indivisible unit. If any part of the transaction fails, the entire transaction is rolled back, and the database returns to its original state.

Consistency: Consistency guarantees that a database transaction takes the database from one valid state to another. If a transaction violates any of the database's constraints, the transaction is rolled back, and the database returns to its original state.

Isolation: Isolation guarantees that each transaction is processed independently of other transactions. Transactions are processed in a way that ensures that the outcome is the same as if they were processed serially.

Durability: Durability guarantees that once a transaction has been processed, it will be permanently stored in the database, even in the event of system failures.

Why Are ACID Databases Important?

ACID databases are important because they provide a high level of reliability and consistency in database transactions. This is essential for many applications where data consistency is critical, such as financial transactions, inventory management, and customer records.

ACID databases ensure that transactions are processed reliably and consistently, even in the event of system failures or other issues. This means that businesses can rely on their database to provide accurate and up-to-date information, even in the face of unexpected events.

In addition, ACID databases provide a strong foundation for data integrity, which is essential for maintaining the trust of customers and stakeholders.

Examples of ACID Databases:

Some examples of ACID databases include:

Oracle Database: Oracle Database is a relational database management system that provides ACID properties.

MySQL: MySQL is an open-source relational database management system that provides ACID properties.

PostgreSQL: PostgreSQL is an open-source relational database management system that provides ACID properties.

What is CDC?

CDC is a technology that captures changes made to a database in real-time, and enables those changes to be used by other applications or databases. CDC captures changes made to tables, columns, and rows in a database, and stores them in a separate log or file.

CDC can be implemented using different techniques depending on the database management system (DBMS) being used.

How Does CDC Work?

CDC works by capturing changes made to a database in real-time, and storing those changes in a separate log or file. This log or file can be used by other applications or databases to replicate the changes made to the original database.

When a change is made to a database, CDC captures the before and after values of the changed data. CDC can also capture the timestamp of the change, the user who made the change, and any metadata associated with the change.

CDC can be configured to capture changes at different levels of granularity, from individual rows to entire tables. CDC can also be configured to capture changes in real-time, or at scheduled intervals.

Advantages of CDC

CDC offers several advantages over traditional data replication techniques, including:

Real-time data capture: CDC captures changes to a database in real-time, which enables real-time data analysis and synchronisation.

Low impact on performance: CDC has a low impact on database performance, since it captures changes in real-time and does not require a complete copy of the database.

Granular data capture: CDC can be configured to capture changes at a granular level, from individual rows to entire tables.

Automated data capture: CDC can be automated, which reduces the need for manual intervention and improves accuracy.

Data integration: CDC enables integration between different databases, applications, and platforms.

Conclusion

CDC is a powerful technology that enables real-time data capture and integration. CDC can be used to replicate data between databases, synchronize data between applications, and enable real-time data analysis. By capturing changes made to a database in real-time, CDC enables organizations to make more informed decisions and respond to changing business needs in real-time. CDC is a valuable tool for organizations that need to integrate data between different databases, applications, and platforms, and it is a critical technology for organizations that require real-time data analysis and synchronization.