Load & Release

Loading a collection is the prerequisite to conducting similarity searches and queries in collections. This page focuses on the procedures for loading and releasing a collection.

Load Collection

When you load a collection, Milvus loads the index files and the raw data of all fields into memory for rapid response to searches and queries. Entities inserted after a collection load are automatically indexed and loaded.

The following code snippets demonstrate how to load a collection.

from pymilvus import MilvusClient

client = MilvusClient(
    uri="http://localhost:19530",
    token="root:Milvus"
)

# 7. Load the collection
client.load_collection(
    collection_name="customized_setup_1"
)

res = client.get_load_state(
    collection_name="customized_setup_1"
)

print(res)

# Output
#
# {
#     "state": "<LoadState: Loaded>"
# }

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

String CLUSTER_ENDPOINT = "http://localhost:19530";
String TOKEN = "root:Milvus";

// 1. Connect to Milvus server
ConnectConfig connectConfig = ConnectConfig.builder()
        .uri(CLUSTER_ENDPOINT)
        .token(TOKEN)
        .build();

MilvusClientV2 client = new MilvusClientV2(connectConfig);

// 6. Load the collection
LoadCollectionReq loadCollectionReq = LoadCollectionReq.builder()
        .collectionName("customized_setup_1")
        .build();

client.loadCollection(loadCollectionReq);

// 7. Get load state of the collection
GetLoadStateReq loadStateReq = GetLoadStateReq.builder()
        .collectionName("customized_setup_1")
        .build();

Boolean res = client.getLoadState(loadStateReq);
System.out.println(res);

// Output:
// true

import { MilvusClient, DataType } from "@zilliz/milvus2-sdk-node";

const address = "http://localhost:19530";
const token = "root:Milvus";
const client = new MilvusClient({address, token});

// 7. Load the collection
res = await client.loadCollection({
    collection_name: "customized_setup_1"
})

console.log(res.error_code)

// Output
// 
// Success
// 

res = await client.getLoadState({
    collection_name: "customized_setup_1"
})

console.log(res.state)

// Output
// 
// LoadStateLoaded
// 

import (
    "context"
    "fmt"
    "log"

    "github.com/milvus-io/milvus/client/v2"
)

defer cli.Close(ctx)

loadTask, err := cli.LoadCollection(ctx, client.NewLoadCollectionOption("customized_setup_1"))
if err != nil {
    // handle error
}

// sync wait collection to be loaded
err = loadTask.Await(ctx)
if err != nil {
    // handle error
}

export CLUSTER_ENDPOINT="http://localhost:19530"
export TOKEN="root:Milvus"

curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/vectordb/collections/load" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
-d '{
    "collectionName": "customized_setup_1"
}'

# {
#     "code": 0,
#     "data": {}
# }

curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/vectordb/collections/get_load_state" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
-d '{
    "collectionName": "customized_setup_1"
}'

# {
#     "code": 0,
#     "data": {
#         "loadProgress": 100,
#         "loadState": "LoadStateLoaded",
#         "message": ""
#     }
# }

Load Specific Fields

Milvus can load only the fields involved in searches and queries, reducing memory usage and improving search performance.

The following code snippet assumes that you have created a collection named customized_setup_2, and there are two fields named my_id and my_vector in the collection.

client.load_collection(
    collection_name="customized_setup_1",
    # highlight-next-line
    load_fields=["my_id", "my_vector"] # Load only the specified fields
    skip_load_dynamic_field=True # Skip loading the dynamic field
)

res = client.get_load_state(
    collection_name="customized_setup_1"
)

print(res)

# Output
#
# {
#     "state": "<LoadState: Loaded>"
# }

// 6. Load the collection
LoadCollectionReq loadCollectionReq = LoadCollectionReq.builder()
        .collectionName("customized_setup_1")
        .loadFields(Arrays.asList("my_id", "my_vector"))
        .build();

client.loadCollection(loadCollectionReq);

// 7. Get load state of the collection
GetLoadStateReq loadStateReq = GetLoadStateReq.builder()
        .collectionName("customized_setup_1")
        .build();

Boolean res = client.getLoadState(loadStateReq);
System.out.println(res);

await client.load_collection({
  collection_name: "customized_setup_1",
  load_fields: ["my_id", "my_vector"], // Load only the specified fields
  skip_load_dynamic_field: true //Skip loading the dynamic field
});

const loadState = client.getCollectionLoadState({
    collection_name: "customized_setup_1",
})

console.log(loadState);

import (
    "context"
    "fmt"
    "log"

    "github.com/milvus-io/milvus/client/v2"
)

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

loadTask, err := cli.LoadCollection(ctx, client.NewLoadCollectionOption("customized_setup_1").
    WithLoadFields("my_id", "my_vector"))
if err != nil {
    // handle error
}

// sync wait collection to be loaded
err = loadTask.Await(ctx)
if err != nil {
    // handle error
}

# REST 缺失

If you choose to load specific fields, it is worth noting that only the fields included in load_fields can be used as filters and output fields in searches and queries. You should always include the names of the primary field and at least one vector field in load_fields.

You can also use skip_load_dynamic_field to determine whether to load the dynamic field. The dynamic field is a reserved JSON field named $meta and saves all non-schema-defined fields and their values in key-value pairs. When loading the dynamic field, all keys in the fields are loaded and available for filtering and output. If all keys in the dynamic field are not involved in metadata filtering and output, set skip_load_dynamic_field to True.

To load more fields after the collection load, you need to release the collection first to avoid possible errors prompted because of index changes.

Release Collection

Searches and queries are memory-intensive operations. To save the cost, you are advised to release the collections that are currently not in use.

The following code snippet demonstrates how to release a collection.

# 8. Release the collection
client.release_collection(
    collection_name="custom_quick_setup"
)

res = client.get_load_state(
    collection_name="custom_quick_setup"
)

print(res)

# Output
#
# {
#     "state": "<LoadState: NotLoad>"
# }

import io.milvus.v2.service.collection.request.ReleaseCollectionReq;


// 8. Release the collection
ReleaseCollectionReq releaseCollectionReq = ReleaseCollectionReq.builder()
        .collectionName("custom_quick_setup")
        .build();

client.releaseCollection(releaseCollectionReq);

GetLoadStateReq loadStateReq = GetLoadStateReq.builder()
        .collectionName("custom_quick_setup")
        .build();
Boolean res = client.getLoadState(loadStateReq);
System.out.println(res);

// Output:
// false

// 8. Release the collection
res = await client.releaseCollection({
    collection_name: "custom_quick_setup"
})

console.log(res.error_code)

// Output
// 
// Success
// 

res = await client.getLoadState({
    collection_name: "custom_quick_setup"
})

console.log(res.state)

// Output
// 
// LoadStateNotLoad
// 

import (
    "context"

    "github.com/milvus-io/milvus/client/v2"
)

err := cli.ReleaseCollection(ctx, client.NewReleaseCollectionOption("custom_quick_setup"))
if err != nil {
    // handle error
}

export CLUSTER_ENDPOINT="http://localhost:19530"
export TOKEN="root:Milvus"

curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/vectordb/collections/release" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
-d '{
    "collectionName": "custom_quick_setup"
}'

# {
#     "code": 0,
#     "data": {}
# }

curl --request POST \
--url "${CLUSTER_ENDPOINT}/v2/vectordb/collections/get_load_state" \
--header "Authorization: Bearer ${TOKEN}" \
--header "Content-Type: application/json" \
-d '{
    "collectionName": "custom_quick_setup"
}'

# {
#     "code": 0,
#     "data": {
#         "loadProgress": 0,
#         "loadState": "LoadStateNotLoaded",
#         "message": ""
#     }
# }