Change data capture, or CDC, is a technology used for data replication that enables low-latency data integration across enterprise data stores. In competitive environments where having accurate, fresh data and up-to-the-minute business intelligence is crucial, CDC database replication technology is essential because it facilitates continuous data replication and real-time data synchronization. In fact, CDC is one of the most important features to consider in any enterprise database replication tool comparison.
CDC for database technology doesn't just help you extract and load data into your data warehouses or other platforms more efficiently—in incremental batches and/or in real time—but also enables zero-downtime system upgrades and database migrations while supporting query offloading, failover system creation, and more.
As a built-in technology, CDC database replication was first introduced into the MS SQL Server environment with the 2006 release of SQL Server Enterprise Edition and, as of 2016, is available with the Standard Edition as well. This built-in CDC for SQL Server functionality reads committed transactions from the database's transaction logs to capture and record DML (Data Manipulation Language) changes (e.g., updates and insertions) that are applied to user tables on which CDC has been enabled. These changes are then stored in change tables on the source database in an easily consumable format for SSIS and other ETL tools.
As a CDC database technology, SQL Server's native change data capture functionality is relatively easy to implement and less intrusive than using timestamp columns or database triggers. However, SQL Server does not have a transport mechanism or the ability to offload change tables from the source database.
In Oracle environments, built-in CDC database replication technology was introduced in 2001 with the release of Oracle 9i and vastly improved with the release of Oracle 10g. Similar to SQL Server's built-in CDC functionality, native CDC for Oracle is a log-based technology that eliminates the need for database triggers. What is different is its use of Oracle Streams, a built-in Oracle database replication feature, as a transport mechanism for data synchronization and the ability to offload change data capture to another database. With the release of Oracle 12c, built-in CDC is no longer supported, leaving Oracle users to switch to Oracle GoldenGate for an additional license fee or find a more affordable alternative.
Qlik Replicate (formerly Attunity Replicate) is an economical, high-performance data replication platform featuring our unique, log-based CDC technology. Our universal database replication tool supports the broadest range of source and target platforms including all major relational databases, making it suitable for both Oracle and SQL Server database replication. Our next-generation CDC technology is non-invasive, using transaction logs for SQL Server and redo logs for Oracle to read data changes from your databases, and facilitates real-time data integration without degrading the performance of your source systems. With Qlik Replicate (formerly Attunity Replicate), there's no need to install agents on either source or target, and our platform works seamlessly with most ETL tools while providing optimized loading directly into your data warehouses.