Milvus limitations

Limitations on the length of an identifier

Identifier type Maximum length (number of characters allowed)
Collection 255
Field 255
Index 255
Partition 255

Rules on naming identifiers

The name of an identifier can only contain numbers, letters, dollar signs ($), and underscores (__). The first character in an identifier must be a letter or the underscore sign.

Limitations on the number of collections and connections

Identifier type Maximum number
Collections 65536
Connections / proxy 65536

Limitations on a single collection

Type Maximum number
Partitions 4096
Shards 256
Fields 256
Indexes 65536
Entities unlimited

Limitations on strings

Type Upper limit (characters)
VARCHAR 65535
VARCHAR will be supported in the 2.0 stable version. More string types will be supported in the future.

Limitations on vector data

Property Maximum number
Dimensions 32768

Limitations on data size per RPC

Operation Data Size (MB)
Insert 512
Search 512
Query 512

Limitations on search params

Params Maximum number
Top K 16384
nq 16384
Due to Pulsar's limitation on the log transmission size (100 MB), Milvus does not support TopK of 16384 on high-dimension vector search in current version. Milvus 2.0.0 will fully support TopK of 16384.
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