Modifying Kafka Topic Configurations

This section describes how to modify following configurations of a Kafka topic on the console.

**Table 1** Kafka topic configuration parameters
Parameter	Description
Synchronous Replication	A message is returned to the client only after the message creation request has been received and the message has been acknowledged by all replicas.
Synchronous Flushing	Enabled: A message is immediately flushed to disk once it is created, bringing higher reliability. Disabled: A message is stored in the memory instead of being immediately flushed to disk once created.
Message Timestamp	Timestamp type of a message. Options: CreateTime: time when the producer created the message. LogAppendTime: time when the broker appended the message to the log.
Max. Message Size	Maximum size of messages to be processed in batches. If message compression is enabled, this parameter indicates the size after compression. If this value is increased and the consumer version is earlier than 0.10.2, the consumers' fetch size must also be increased so that they can obtain the latest value.

Modifying Synchronous Replication, Synchronous Flushing, Message Timestamp, or Max. Message Size does not require instance restart.

Log in to the console.
Click in the upper left corner to select a region.

Select the region where your Kafka instance is located.
Click and choose Application > Distributed Message Service for Kafka to open the console of DMS for Kafka.
Click the desired Kafka instance to view the instance details.
In the navigation pane, choose Topics.
Modify topic configurations in either of the following ways:
- Select one or more topics and click Edit Topic above the topic list.
- In the row containing the desired topic, click Edit.
In the Edit Topic dialog box, change configurations and click OK.
- If there is only one replica, Synchronous Replication cannot be enabled.
- After enabling synchronous replication, set acks to all or –1 on the client. Otherwise, this function will not take effect.