Limits

Item	Description	Valid value
Active shards	The maximum number of active shards in each topic.	(0,256]
Total shards	The maximum number of total shards in each topic.	(0,512]
HTTP body size	The maximum body size in HTTP requests.	4 MB
String size	The maximum size of a single string in data.	2 MB
Wait time for merge and split operations on new shards	The period of time that you must wait to perform merge or split operations after a shard is created.	5s
Queries per second (QPS)	The maximum write QPS on each shard. Multiple records written at a time are considered one record.	2000
Throughput	The maximum write throughput per second on each shard.	5 MB/s
Projects	The maximum number of projects that can be created within each Alibaba Cloud account.	50
Topics	The maximum number of topics that can be created in each project. Contact administrators if you have other requirements.	500
Time-to-live (TTL) period of a topic	The retention period of data in each topic. Unit: day.	[1,7]
Records written at a time	The maximum number of records that can be written to a shard at a time.	10000

Naming conventions

Term	Description	Character length	Rule
Project	The name of a project.	[3,32]	The name can contain letters, digits, and underscores (_). It is not case-sensitive and must start with a letter.
Topic	The name of a topic.	[1,128]	The name can contain letters, digits, and underscores (_). It is not case-sensitive and must start with a letter.
Field	The name of a field.	[1,128]	The name can contain letters, digits, and underscores (_). It is not case-sensitive and must start with a letter. Invalid field name: SYSTEM_TIME.