Question
Answer and Explanation
Checking what was changed in Change Data Capture (CDC) typically involves examining the output or logs generated by your CDC system. The specific method depends heavily on the CDC tool you are using, but here are some common approaches:
1. Review CDC Output Streams:
- Most CDC systems output changes as a stream of events. These events usually include information about the type of change (insert, update, delete), the affected table, and the actual data that was changed. You can inspect these streams to see what modifications occurred.
2. Examine CDC Logs:
- CDC tools often maintain logs that record the changes they capture. These logs can provide a detailed history of modifications, including timestamps, affected rows, and the specific data that was altered. Check the documentation for your CDC tool to find the location and format of these logs.
3. Use CDC Monitoring Tools:
- Many CDC solutions come with monitoring dashboards or tools that allow you to visualize and track changes. These tools often provide a user-friendly interface to view change events, filter by table or time, and analyze the impact of changes.
4. Query Target Databases:
- If your CDC system replicates changes to a target database, you can query the target tables to see the results of the changes. By comparing the target data with the source data, you can identify what was modified. This approach is useful for verifying that the CDC process is working correctly.
5. Utilize CDC Metadata:
- Some CDC systems provide metadata about the changes, such as the user who made the change or the application that initiated it. This metadata can be valuable for auditing and understanding the context of the changes.
6. Specific Tool Examples:
- Debezium: Debezium outputs change events in formats like JSON or Avro. You can consume these events using Kafka or other message brokers and inspect the data.
- AWS DMS (Database Migration Service): AWS DMS provides CloudWatch logs and metrics that can be used to monitor changes. You can also query the target database to verify the changes.
- SQL Server Change Data Capture: SQL Server CDC stores change data in change tables. You can query these tables to see the changes that have occurred.
In summary, to check what was changed in CDC, you need to access the output streams, logs, monitoring tools, or target databases associated with your specific CDC system. Always refer to the documentation of your CDC tool for the most accurate and detailed information.