CollectionSchema

This class defines the schema of a collection by specifying its fields and dynamic-field settings. An alias CollectionSchemaPtr (a std::shared_ptr<CollectionSchema>) is provided for convenience. Pass the pointer to CreateCollectionRequest::WithCollectionSchema() when creating a collection.

CollectionSchema();
explicit CollectionSchema(std::string name, std::string desc = "",
                          int32_t shard_num = 1,
                          bool enable_dynamic_field = true);

using CollectionSchemaPtr = std::shared_ptr<CollectionSchema>;

PARAMETERS:

• name (std::string)

  Sets the Collection name. In MilvusClientV2 this is set via CreateCollectionRequest::WithCollectionName() and this constructor parameter is ignored.

• desc (std::string)

  Sets the optional human-readable description. Default: "".

• shard_num (int32_t)

  Sets the number of shards. Must be greater than 0. Default: 1. In MilvusClientV2, set this via CreateCollectionRequest::WithNumShards() instead.

• enable_dynamic_field (bool)

  When true, entities may contain fields that are not declared in the schema. The extra fields are stored internally in a JSON field named $meta. Default: true.

Methods

Adding fields:

• bool AddField(const FieldSchema& field_schema)

  Appends a regular field to the schema. Returns true on success. Use FieldSchema to specify the field name, DataType, and type-specific settings (e.g., WithDimension() for vector fields, WithMaxLength() for VARCHAR fields, WithPrimaryKey(true) for the primary key).

• const std::vector<FieldSchema>& Fields() const

  Returns the list of field schemas added so far.

• bool AddStructField(const StructFieldSchema& field_schema)

  Appends a struct field (multi-vector type). Returns true on success.

• const std::vector<StructFieldSchema>& StructFields() const

  Returns the list of struct field schemas.

• void AddFunction(const FunctionPtr& function)

  Attaches a built-in function (e.g., a BM25 tokenizer function) to the schema.

• const std::vector<FunctionPtr>& Functions() const

  Returns the list of functions attached to the schema.

Dynamic field:

• void SetEnableDynamicField(bool enable_dynamic_field)

  Enables or disables dynamic fields at runtime.

• bool EnableDynamicField() const

  Returns whether dynamic fields are enabled.

Introspection:

• std::string PrimaryFieldName() const

  Returns the name of the primary key field.

• std::unordered_set<std::string> AnnsFieldNames() const

  Returns the names of all vector (ANNS) fields in the schema.

Example

#include "milvus/MilvusClientV2.h"
#include <milvus/MilvusClientV2.h>
using namespace milvus;

// Build a schema: int64 primary key, varchar, int8, and a 128-dim float vector
CollectionSchemaPtr schema = std::make_shared<CollectionSchema>();
schema->AddField(FieldSchema("id",  DataType::INT64,        "primary key").WithPrimaryKey(true));
schema->AddField(FieldSchema("name",DataType::VARCHAR,      "user name").WithMaxLength(200));
schema->AddField(FieldSchema("age", DataType::INT8,         "user age"));
schema->AddField(FieldSchema("vec", DataType::FLOAT_VECTOR, "embedding").WithDimension(128));

auto client = MilvusClientV2::Create();
client->Connect(ConnectParam("http://localhost:19530").WithToken("root:Milvus"));

auto status = client->CreateCollection(
    CreateCollectionRequest()
        .WithCollectionName("my_collection")
        .WithCollectionSchema(schema)
        .AddIndex(IndexDesc("vec", "", IndexType::HNSW, MetricType::COSINE))
        .WithConsistencyLevel(ConsistencyLevel::STRONG));