Create a Collection

This topic describes how to create a collection in Milvus.

A collection consists of one or more partitions. While creating a new collection, Milvus creates a default partition _default. See Glossary - Collection for more information.

The following example builds a two-shard collection named book, with a primary key field named book_id, an INT64 scalar field named word_count, and a two-dimensional floating-point vector field named book_intro. Real applications will likely use much higher dimensional vectors than the example.

Prepare Schema

First, prepare necessary parameters, including the field schema, collection schema, and collection name.

Before defining a collection schema, create a schema for each field in the collection. To reduce the complexity in data inserts, Milvus allows you to specify a default value for each scalar field, excluding a primary key field. This indicates that if you leave a field empty when inserting data, the default value you configured for this field during field schema creation will be used.

from pymilvus import CollectionSchema, FieldSchema, DataType
book_id = FieldSchema(
  name="book_id",
  dtype=DataType.INT64,
  is_primary=True,
)
book_name = FieldSchema(
  name="book_name",
  dtype=DataType.VARCHAR,
  max_length=200,
  # The default value will be used if this field is left empty during data inserts or upserts.
  # The data type of `default_value` must be the same as that specified in `dtype`.
  default_value="Unknown"
)
word_count = FieldSchema(
  name="word_count",
  dtype=DataType.INT64,
  # The default value will be used if this field is left empty during data inserts or upserts.
  # The data type of `default_value` must be the same as that specified in `dtype`.
  default_value=9999
)
book_intro = FieldSchema(
  name="book_intro",
  dtype=DataType.FLOAT_VECTOR,
  dim=2
)
schema = CollectionSchema(
  fields=[book_id, book_name, word_count, book_intro],
  description="Test book search",
  enable_dynamic_field=True
)
collection_name = "book"

import { DataType } from "@zilliz/milvus2-sdk-node";
const params = {
  collection_name: "book",
  description: "Test book search",
  fields: [
    {
      name: "book_intro",
      description: "",
      data_type: DataType.FloatVector,
      dim: 2,
    },
    {
      name: "book_id",
      data_type: DataType.Int64,
      is_primary_key: true,
      description: "",
    },
    {
      name: "book_name",
      data_type: DataType.VarChar,
      max_length: 256,
      description: "",
    },
    {
      name: "word_count",
      data_type: DataType.Int64,
      description: "",
    },
  ],
  enableDynamicField: true
};

var (
    collectionName = "book"
)
schema := &entity.Schema{
  CollectionName: collectionName,
  Description:    "Test book search",
  Fields: []*entity.Field{
    {
      Name:       "book_id",
      DataType:   entity.FieldTypeInt64,
      PrimaryKey: true,
      AutoID:     false,
    },
    {
      Name:       "word_count",
      DataType:   entity.FieldTypeInt64,
      PrimaryKey: false,
      AutoID:     false,
    },
    {
      Name:     "book_intro",
      DataType: entity.FieldTypeFloatVector,
      TypeParams: map[string]string{
          "dim": "2",
      },
    },
  },
  EnableDynamicField: true,
}

FieldType fieldType1 = FieldType.newBuilder()
        .withName("book_id")
        .withDataType(DataType.Int64)
        .withPrimaryKey(true)
        .withAutoID(false)
        .build();
FieldType fieldType2 = FieldType.newBuilder()
        .withName("word_count")
        .withDataType(DataType.Int64)
        .build();
FieldType fieldType3 = FieldType.newBuilder()
        .withName("book_intro")
        .withDataType(DataType.FloatVector)
        .withDimension(2)
        .build();
CreateCollectionParam createCollectionReq = CreateCollectionParam.newBuilder()
        .withCollectionName("book")
        .withDescription("Test book search")
        .withShardsNum(2)
        .addFieldType(fieldType1)
        .addFieldType(fieldType2)
        .addFieldType(fieldType3)
        .withEnableDynamicField(true)
        .build();

create collection -c book -f book_id:INT64:book_id -f word_count:INT64:word_count -f book_intro:FLOAT_VECTOR:2 -p book_id

curl -X 'POST' \
  '${MILVUS_HOST}:${MILVUS_PORT}/v1/vector/collections/create' \
  -H 'Authorization: Bearer ${TOKEN}' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
       "dbName": "default",   
       "collectionName": "medium_articles",
       "dimension": 256,
       "metricType": "L2",
       "primaryField": "id",
       "vectorField": "vector"
      }'

{
    "code": 200,
    "data": {}
}

Create a collection with the schema

Then, create a collection with the schema you specified above.

from pymilvus import Collection
collection = Collection(
    name=collection_name,
    schema=schema,
    using='default',
    shards_num=2
    )

await milvusClient.createCollection(params);

err = milvusClient.CreateCollection(
    context.Background(), // ctx
    schema,
    2, // shardNum
)
if err != nil {
    log.Fatal("failed to create collection:", err.Error())
}

milvusClient.createCollection(createCollectionReq);

Limits

Resource configuration

Parameter default_value

• default_value is available only for non-array and non-JSON scalar fields.
• default_value does not apply to the primary key.
• The data type of default_value must be the same as that specified in dtype. Otherwise, an error can occur.
• In the case of using auto_id, it’s not allowed to set all the remaining fields to use default values. That is, when performing insert or upsert operations, you need to specify values for at least one field. Otherwise, an error can occur.

What’s next

• Learn more basic operations of Milvus:
  • Insert data into Milvus
  • Create a partition
  • Build an index for vectors
  • Conduct a vector search
  • Conduct a hybrid search