Use Limits

Last updated:2026-01-20 16:37:21

Use Limits

Last updated: 2026-01-20 16:37:21

This document lists the limits on certain metrics and performance in TDMQ for CKafka (CKafka). Be careful not to exceed the limits during use to avoid exceptions.
Instances
Category
Item
Description
Version
CKafka server major version
The server version number may be 2.4, 2.8, or 3.2. Major version upgrade is currently not supported by the console.
Security management
ZooKeeper exposure
Not supported.
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Underlying resource exposure
This is not supported to avoid risks caused by user operations.
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Client usage
It is recommended to use the CKafka console or TencentCloud API for managing metadata of clusters and topics.
It is not recommended to use AdminClient to directly perform metadata operations such as creating topics and modifying partitions, as this may cause data inconsistency in the console. Such operations are planned to be prohibited in the future. 
Performance and reliability
Maximum number of connections per instance
The maximum number of connections per instance is 50,000. If this limit is exceeded, no connections can be created on the client. If this limit is deemed inappropriate for your actual services, contact us to request a modification.
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Message size
The message size cannot exceed 12 MB. Otherwise, message sending will fail.
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Partition throughput
In the case of ack = 1, the throughput of a single CKafka partition is 30–60 MB/s due to factors such as CKafka partition architecture, business data size, and request frequency.
In case of ack = -1 (strong consistency), it is recommended that the throughput of a single CKafka partition be 10–20 MB/s to avoid unstable time consumption of requests caused by factors such as CKafka partition architecture, business data size, and request frequency.
In scenarios involving idempotence or transactions, the load on the CKafka server will further increase, which may impact the maximum throughput per partition. If low latency is critical for your business, it is recommended to conduct load testing using different cluster specifications.
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Limits on concurrent operations in the console
Certain control operations may involve operations and modifications of instance metadata. The issue of inconsistency may occur when the concurrency is high, affecting the underlying request distribution. Therefore, certain APIs are locked to limit the request concurrency. Currently, a maximum of 20 concurrent requests (including TencentCloud API calling by SDKs) are allowed for a single instance per second to improve the stability and success rate of operations.
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Data reliability
Due to the replica synchronization and acknowledgment mechanisms of CKafka, data loss may occur in extreme scenarios. For example, given 2 replicas and ack = 1, data may be lost if the replicas are not synchronized when the leader is switched in a partition. If your business cannot tolerate data loss, please refer to High Data Reliability for client configuration.
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Duration
Featuring high-traffic and high-throughput message queues, CKafka cannot guarantee low latency for each request. It is recommended to set the timeout duration to:
30 seconds for the producer in case of ack = 1.
60 seconds for the producer in case of ack = –1.
60 seconds for the consumer.
Network connection
Multi-route
For one instance, only 1 public network route can be created, and a maximum of 5 routes can be created (excluding the primary route created when the instance is created).
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Virtual Private Cloud (VPC) route
CKafka will create a primary route for the VPC network selected when an instance is created. This primary route cannot be deleted.
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Public network bandwidth
By default, the free public network bandwidth of 3 Mbps is provided, which can be upgraded for Pro Edition instances.
Instance management
Region properties of instances
Once created, instances cannot be modified.
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Tag
The maximum number of tags for each cloud resource is 50.
Note:
Due to factors such as partition architecture, service data size, request frequency, and physical layer stability, CKafka cannot guarantee low latency for every request.
We strive to guarantee that:
The monthly production time compliance rate of a single instance meets the SLA for the instance.
The monthly consumption time compliance rate of a single instance meets the SLA for the instance.
The calculation formulas are as follows:
Monthly production time compliance rate = (Number of minutes where the production time at the 999th percentile has not exceeded 30 seconds in a month/Total number of service minutes in a month) x 100%.
Monthly consumption time compliance rate = (Number of minutes where the consumption time at the 999th percentile has not exceeded 60 seconds in a month/Total number of service minutes in a month) x 100%.
Topic
Item
Description
Number of topics/Total number of partitions
When the total number of partitions (including replica partitions) for all topics (manually and automatically created topics) under an instance reaches the upper limit, you will be unable to create new topics. In this case, you can increase the partition limit to expand the capacity for creating topics.
Number of partitions for a single topic
For stability reasons, it is recommended to set the number of partitions (excluding replicas) for a single topic to no more than 200.
Number of replicas
1 to 3 replicas can be configured for Advanced Edition or Pro Edition instances. To ensure data reliability, a single replica is not recommended for production environments. Topics are created with 2 replicas by default. If higher availability is required for services, you can configure 3 replicas.
Consumer group
Item
Description
Number of consumer groups
For Standard Edition instances, it is recommended that the number of consumer groups be no more than 50.
For Advanced Edition and Pro Edition instances, it is recommended that the number of consumer groups be no more than 500. You can contact us to apply for an upgrade.
Consumer group name
A consumer group name can contain only letters, digits, underscores, hyphens (-), and periods (.), excluding special characters that may cause monitoring data display failure.
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Category	Item	Description
Version	CKafka server major version	The server version number may be 2.4, 2.8, or 3.2. Major version upgrade is currently not supported by the console.
Security management	ZooKeeper exposure	Not supported.
		Underlying resource exposure	This is not supported to avoid risks caused by user operations.
		Client usage	It is recommended to use the CKafka console or TencentCloud API for managing metadata of clusters and topics. It is not recommended to use AdminClient to directly perform metadata operations such as creating topics and modifying partitions, as this may cause data inconsistency in the console. Such operations are planned to be prohibited in the future.
Performance and reliability	Maximum number of connections per instance	The maximum number of connections per instance is 50,000. If this limit is exceeded, no connections can be created on the client. If this limit is deemed inappropriate for your actual services, contact us to request a modification.
		Message size	The message size cannot exceed 12 MB. Otherwise, message sending will fail.
		Partition throughput	In the case of ack = 1, the throughput of a single CKafka partition is 30–60 MB/s due to factors such as CKafka partition architecture, business data size, and request frequency. In case of ack = -1 (strong consistency), it is recommended that the throughput of a single CKafka partition be 10–20 MB/s to avoid unstable time consumption of requests caused by factors such as CKafka partition architecture, business data size, and request frequency. In scenarios involving idempotence or transactions, the load on the CKafka server will further increase, which may impact the maximum throughput per partition. If low latency is critical for your business, it is recommended to conduct load testing using different cluster specifications.
		Limits on concurrent operations in the console	Certain control operations may involve operations and modifications of instance metadata. The issue of inconsistency may occur when the concurrency is high, affecting the underlying request distribution. Therefore, certain APIs are locked to limit the request concurrency. Currently, a maximum of 20 concurrent requests (including TencentCloud API calling by SDKs) are allowed for a single instance per second to improve the stability and success rate of operations.
		Data reliability	Due to the replica synchronization and acknowledgment mechanisms of CKafka, data loss may occur in extreme scenarios. For example, given 2 replicas and ack = 1, data may be lost if the replicas are not synchronized when the leader is switched in a partition. If your business cannot tolerate data loss, please refer to High Data Reliability for client configuration.
		Duration	Featuring high-traffic and high-throughput message queues, CKafka cannot guarantee low latency for each request. It is recommended to set the timeout duration to: 30 seconds for the producer in case of ack = 1. 60 seconds for the producer in case of ack = –1. 60 seconds for the consumer.
Network connection	Multi-route	For one instance, only 1 public network route can be created, and a maximum of 5 routes can be created (excluding the primary route created when the instance is created).
		Virtual Private Cloud (VPC) route	CKafka will create a primary route for the VPC network selected when an instance is created. This primary route cannot be deleted.
		Public network bandwidth	By default, the free public network bandwidth of 3 Mbps is provided, which can be upgraded for Pro Edition instances.
Instance management	Region properties of instances	Once created, instances cannot be modified.
Instance management		Tag	The maximum number of tags for each cloud resource is 50.

Item	Description
Number of topics/Total number of partitions	When the total number of partitions (including replica partitions) for all topics (manually and automatically created topics) under an instance reaches the upper limit, you will be unable to create new topics. In this case, you can increase the partition limit to expand the capacity for creating topics.
Number of partitions for a single topic	For stability reasons, it is recommended to set the number of partitions (excluding replicas) for a single topic to no more than 200.
Number of replicas	1 to 3 replicas can be configured for Advanced Edition or Pro Edition instances. To ensure data reliability, a single replica is not recommended for production environments. Topics are created with 2 replicas by default. If higher availability is required for services, you can configure 3 replicas.

Item	Description
Number of consumer groups	For Standard Edition instances, it is recommended that the number of consumer groups be no more than 50. For Advanced Edition and Pro Edition instances, it is recommended that the number of consumer groups be no more than 500. You can contact us to apply for an upgrade.
Consumer group name	A consumer group name can contain only letters, digits, underscores, hyphens (-), and periods (.), excluding special characters that may cause monitoring data display failure.

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Instances

Topic

Consumer group