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Advanced features

You can use the following advanced features with transactions in Pulsar.

Ack batch messages​

If you want to acknowledge batch messages with transactions, set acknowledgmentAtBatchIndexLevelEnabled to true in the broker.conf or standalone.conf file.

acknowledgmentAtBatchIndexLevelEnabled=true

This example enables batch messages ack in transactions in the consumer builder.

Consumer<byte[]> consumer = pulsarClient
    .newConsumer()
    .topic(transferTopic)
    .subscriptionName("transaction-sub")
    .subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
    .subscriptionType(SubscriptionType.Shared)
    .enableBatchIndexAcknowledgment(true) // enable batch index acknowledgment
    .subscribe();

Enable authentication​

If you want to enable authentication with transactions, follow the steps below.

  1. Grant "consume" permission to the persistent://pulsar/system/transaction_coordinator_assign topic.

  2. Configure authentication in a Pulsar client.

Guarantee exactly-once semantics​

If you want to guarantee exactly-once semantics with transactions, you can enable message deduplication at the broker, namespace, or topic level.

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