What is the effect of setting delta.enableChangeDataFeed to true in Delta Lake?

Setting delta.enableChangeDataFeed to true in Delta Lake enables the change data capture (CDC) functionality, which creates a log of all changes made to the data within a Delta table. This allows users to track historical changes, making it easier to understand how data evolves over time. When this feature is enabled, it records metadata about inserts, updates, and deletes, allowing for a comprehensive view of changes that have occurred since the last read.

This feature is particularly useful for applications that require data synchronization between different systems or for use cases that involve auditing and data lineage. By maintaining a history of changes, it supports analytical queries that need to analyze how data has changed, improving visibility and governance of the data.

The other options do not accurately capture the core functionality of change data feed. For instance, while the option regarding changes being fed to a target seems relevant, it does not reflect the primary advantage of tracking changes historically. The option about triggers automatically updating source data implies an active mechanism that is not part of this setting's purpose. Additionally, the option about disabling prior version retention policies does not relate to the function of enabling the change data feed. Hence, the focus on creating a log for historical tracking is what fundamentally describes the benefit of enabling