Kafka producers can be configured to be idempotent, which means they use a unique sequence number for each message to avoid duplicate writes.
This ensures that even if a message is sent multiple times due to retries, it will only be written once
Transactional Producers: Producers can send messages in transactions, ensuring that either all messages in a transaction are committed or none are. This prevents partial writes
Producer Configuration:
acks=all (or acks=-1):
Ensures that the leader broker waits for acknowledgment from all in-sync replicas before considering a write successful
enable.idempotence=true
Enables idempotent producer functionality, which prevents duplicate messages in case of retries
Duplicate messages are detected and discarded.
Transactions
Configured with transactional.id to enable transactional behavior for exactly-once semantics
Consumer Side
Idempotent Consumption:
Consumers should ensure that processing logic is idempotent.
Consumers should handle duplicate messages gracefully
This means, processing a message multiple times does not change the outcome
Transactional Consumers:
Kafka allows consumers to commit offsets as part of a transaction, ensuring that offsets are committed only if the processing of messages is successful.
This prevents reprocessing of messages
Consumer Configuration:
enable.auto.commit=false
Disables automatic offset commits to ensure that offsets are only committed after successful message processing
Consumers commit offsets manually after successful processing within a transaction.
Transaction Management
When using transactions, ensure that consumer offset commits are handled as part of the transaction to avoid inconsistencies