This topic describes the limits of Message Queue for Apache Kafka. To prevent the program from exiting unexpectedly when you use Message Queue for Apache Kafka, do not exceed the limits.

The following table describes the limits of Message Queue for Apache Kafka.

Item Status Description
Maximum number of topics or partitions Supported. Messages are stored and scheduled based on partitions in Message Queue for Apache Kafka. Each topic consists of multiple partitions. If an excessive number of topics or partitions exist, storage fragmentation occurs. This reduces the performance and stability of your cluster.
Decrease in the number of partitions of a topic Not supported. This is due to the design constraints of Apache Kafka.
Exposed ZooKeeper Not supported. You do not need to access ZooKeeper to use clients in Apache Kafka V0.9.0 and later. In Message Queue for Apache Kafka, ZooKeeper is partially shared. For security purposes, it is not exposed. You do not need to understand how ZooKeeper works.
Logons to the machines on which Message Queue for Apache Kafka is deployed Not supported. None.
Supported versions V0.10.x to V2.2.x.
  • Version 2.2.x is compatible with versions 0.10.x and 0.9.0.
  • Version 0.10.x is compatible with version 0.9.0.
  • For information about how to upgrade an instance from V0.10.x to V2.2.x, see Upgrade the instance version.
Partition-to-topic ratio 1:1. The number of available topics is closely related to the total number of partitions. For example, if your alikafka.hw.2xlarge instance provides 1,050 partitions (50 purchased and 1,000 provided free of charge), the number of available topics is 1,050.
Partition-to-consumer group ratio 1:2. The number of available consumer groups is closely related to the total number of partitions. For example, if your alikafka.hw.2xlarge instance provides 1,050 partitions (50 purchased and 1,000 provided free of charge), the number of available consumer groups is 2,100.
Change of the region for an instance Not supported. After an instance is purchased and deployed, its region is closely associated with the physical resources and cannot be changed. If you want to change the region of an instance, release the instance and purchase a new instance.
Change of the network properties for an instance Supported. You can modify the network properties of an instance based on your business requirements. For more information, see Upgrade instance specifications.
Message size 10 MB. The maximum message size is 10 MB. Messages that are larger than 10 MB in size cannot be sent. If you want to increase the maximum message size, submit a ticket to contact technical support.
Monitoring and alerting Supported. The data latency is 1 minute.
Number of client connections to each broker 1,000. Message Queue for Apache Kafka clients must establish socket connections to brokers to send or consume messages. If the number of client connections to a broker exceeds 1,000, the broker occupies a large number of resources to maintain the connections. This can compromise the stability of the broker. We recommend that you establish no more than 1,000 client connections to each broker.
Endpoint Determined by the edition purchased.
  • Standard Edition: supports the default and SSL endpoints.
  • Professional Edition: supports the default, SSL, and SASL endpoints.
Setting of the cloud disk to one partition Supported. However, this may cause service unavailability during server downtime or service upgrade. We recommend that you set more than one partition. If your application requires you to set only one partition, we recommend that you use local storage.
Note The latest Message Queue for Apache Kafka version does not support instance purchases based on the number of topics. If your existing instances were purchased based on the number of topics, the number of available partitions is the number of topics multiplied by 16, and the number of consumer groups is twice the number of topics. For a Professional Edition instance purchased based on the number of topics, the number of available topics is twice the number of purchased topics.