Kafka provides configurable options for message retention and cleanup, which allow administrators to control how long messages are retained in Kafka and when they are deleted.
Kafka’s retention policy is based on the concept of log compaction, which is a mechanism that ensures that Kafka retains at least one copy of each message key within a specified retention period, even if the messages are updated or deleted.
Kafka provides two main options for message retention:
1. Time-based retention: Administrators can configure a time-based retention period for each topic, which determines how long messages are retained in Kafka before they are deleted. Kafka uses the message timestamps to determine when messages expire and should be deleted.
2. Size-based retention: Administrators can also configure a size-based retention policy, which determines how much data is retained in Kafka before older messages are deleted. This can be configured to limit the total size of the Kafka logs or the size of individual partitions.
In addition to retention policies, Kafka also provides configurable options for log cleanup and deletion. Kafka uses a background thread to periodically clean up old log segments and delete expired messages based on the configured retention policies. Kafka also provides an option to delete messages based on the number of partitions, which can be useful for topics with high message throughput.
Overall, Kafka’s message retention and cleanup options provide administrators with fine-grained control over how long messages are retained in Kafka and when they are deleted, allowing for efficient use of storage and efficient processing of data.