Alter Collection Field

You can alter the properties of a collection field to change column constraints or enforce stricter data integrity rules.

This page covers field property changes, not schema-shape changes such as adding or dropping fields. To add scalar fields or drop fields from an existing collection, refer to Alter Collection Schema.

📘Notes

• Each collection consists of only one primary field. Once set during collection creation, you cannot change the primary field or alter its properties.

• Each collection can have only one partition key. Once set during collection creation, you cannot change the partition key.

Alter VarChar field

A VarChar field has a property named max_length, which constrains the maximum number of characters the field values can contain. You can change the max_length property.

The following example assumes the collection has a VarChar field named varchar and sets its max_length property.

Python

python

from pymilvus import MilvusClient

client = MilvusClient(
    uri="YOUR_CLUSTER_ENDPOINT",
    token="YOUR_CLUSTER_TOKEN"
)

client.alter_collection_field(
    collection_name="my_collection",
    field_name="varchar",
    field_params={
        "max_length": 1024
    }
)

Java

java

import io.milvus.v2.client.MilvusClientV2;
import io.milvus.v2.client.ConnectConfig;
import io.milvus.v2.service.collection.request.*;

ConnectConfig config = ConnectConfig.builder()
        .uri("YOUR_CLUSTER_ENDPOINT")
        .token("YOUR_CLUSTER_TOKEN")
        .build();
MilvusClientV2 client = new MilvusClientV2(config);

client.alterCollectionField(AlterCollectionFieldReq.builder()
        .collectionName("my_collection")
        .fieldName("varchar")
        .property("max_length", "1024")
        .build());

NodeJS

javascript

await client.alterCollectionFieldProperties({
  collection_name: LOAD_COLLECTION_NAME,
  field_name: 'varchar',
  properties: { max_length: 1024 },
});

Go

go

import (
    "context"
    "fmt"

    "github.com/milvus-io/milvus/client/v2/entity"
    "github.com/milvus-io/milvus/client/v2/milvusclient"
    "github.com/milvus-io/milvus/pkg/v2/common"
)

ctx, cancel := context.WithCancel(context.Background())
defer cancel()

milvusAddr := "YOUR_CLUSTER_ENDPOINT"

client, err := milvusclient.New(ctx, &milvusclient.ClientConfig{
    Address: milvusAddr,
})
if err != nil {
    fmt.Println(err.Error())
    // handle error
}
defer client.Close(ctx)

err = client.AlterCollectionFieldProperty(ctx, milvusclient.NewAlterCollectionFieldPropertiesOption(
    "my_collection", "varchar").WithProperty(common.MaxLengthKey, 1024))
if err != nil {
    fmt.Println(err.Error())
    // handle error
}

cURL

bash

# restful
curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/collections/fields/alter_properties" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
--header "Request-Timeout: 10" \
--data '{
    "collectionName": "my_collection",
    "field_name": "varchar",
    "properties": {
        "max_length": "1024"
    }
}'

C++

c++

#include "milvus/MilvusClientV2.h"

auto client = milvus::MilvusClientV2::Create();

milvus::ConnectParam connect_param{"YOUR_CLUSTER_ENDPOINT", "YOUR_CLUSTER_TOKEN"};
auto status = client->Connect(connect_param);
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

status = client->AlterCollectionFieldProperties(milvus::AlterCollectionFieldPropertiesRequest()
                    .WithCollectionName("my_collection")
                    .WithFieldName("varchar")
                    .AddProperty("max_length", "1024"));
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

Alter ARRAY field

An array field has two properties, namely element_type and max_capacity. The former determines the data type of the elements in an array, while the latter constrains the maximum number of elements in the array. You can change the max_capacity property only.

The following example assumes the collection has an array field named array and sets its max_capacity property.

Python

python

client.alter_collection_field(
    collection_name="my_collection",
    field_name="array",
    field_params={
        "max_capacity": 64
    }
)

Java

java

client.alterCollectionField(AlterCollectionFieldReq.builder()
        .collectionName("my_collection")
        .fieldName("array")
        .property("max_capacity", "64")
        .build());

NodeJS

javascript

await client.alterCollectionFieldProperties({
  collection_name: "my_collection",
  field_name: 'array',
  properties: { 
      max_capacity: 64 
  }
});

Go

go

err = client.AlterCollectionFieldProperty(ctx, milvusclient.NewAlterCollectionFieldPropertiesOption(
    "my_collection", "array").WithProperty(common.MaxCapacityKey, 64))
if err != nil {
    fmt.Println(err.Error())
    // handle error
}

cURL

bash

# restful
curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/collections/fields/alter_properties" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
--header "Request-Timeout: 10" \
--data '{
    "collectionName": "my_collection",
    "field_name": "array",
    "properties": {
        "max_capacity": "64"
    }
}'

C++

c++

auto status = client->AlterCollectionFieldProperties(milvus::AlterCollectionFieldPropertiesRequest()
                                                .WithCollectionName("my_collection")
                                                .WithFieldName("array")
                                                .AddProperty("max_capacity", "64"));
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

Alter field-level mmap settings

Memory mapping (Mmap) enables direct memory access to large files on disk, allowing Zilliz Cloud to store indexes and data in both memory and hard drives. This approach helps optimize data placement policy based on access frequency, expanding storage capacity for collections without impacting search performance.

The following example assumes the collection has a field named doc_chunk and sets its mmap_enabled property.

Python

python

client.alter_collection_field(
    collection="my_collection",
    field_name="doc_chunk",
    properties={"mmap.enabled": True}
)

Java

java

client.alterCollectionField(AlterCollectionFieldReq.builder()
        .collectionName("my_collection")
        .fieldName("doc_chunk")
        .property("mmap.enabled", "True")
        .build());

NodeJS

javascript

await client.alterCollectionProperties({
  collection_name: "my_collection",
  field_name: 'doc_chunk',
  properties: { 
      'mmap.enabled': true, 
  }
});

Go

go

err = client.AlterCollectionFieldProperty(ctx, milvusclient.NewAlterCollectionFieldPropertiesOption(
    "my_collection", "doc_chunk").WithProperty(common.MmapEnabledKey, true))
if err != nil {
    fmt.Println(err.Error())
    // handle error
}

cURL

bash

# restful
curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/collections/fields/alter_properties" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
--header "Request-Timeout: 10" \
--data '{
    "collectionName": "my_collection",
    "field_name": "doc_chunk",
    "properties": {
        "mmap.enabled": True
    }
}'

C++

c++

auto status = client->AlterCollectionFieldProperties(milvus::AlterCollectionFieldPropertiesRequest()
                                                    .WithCollectionName("my_collection")
                                                    .WithFieldName("doc_chunk")
                                                    .AddProperty("mmap.enabled", "true"));
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}