queryAsync()

Queries entities in a collection asynchronously and returns a future.

Java

public CompletableFuture<QueryResp> queryAsync(QueryReq request)

This method uses the same request parameters as query() but returns a CompletableFuture<QueryResp> immediately. Use the returned future to consume the result or handle the exceptional completion when the operation fails.

Request Syntax

Java

CompletableFuture<QueryResp> future = client.queryAsync(QueryReq.builder()
    .collectionName(String collectionName)
    .filter(String filter)
    .outputFields(List<String> outputFields)
    .build());

For the full list of QueryReq builder methods, refer to query().

RETURN TYPE:

CompletableFuture<QueryResp>

RETURNS:

A future completed with a QueryResp object that contains query rows and execution metrics, or completed exceptionally when the operation fails. The QueryResp object exposes the following getters:

• getQueryResults() (List<QueryResult>) -

  The query result rows. Each QueryResult has the following getters:

  • getEntity() (Map<String, Object>) -

    The field values of the result row.

  • getElementOffset() (Long) -

    For struct-array element-level queries (via element_filter), the index of the matched element within the array. Null for ordinary queries.

• getSessionTs() (long) -

  The session timestamp used for the query.

• getCost() (Long) -

  The time cost of the query operation, in milliseconds.

• getScannedRemoteBytes() (Long) -

  The number of bytes scanned from remote storage.

• getScannedTotalBytes() (Long) -

  The total number of bytes scanned during the query.

• getCacheHitRatio() (Float) -

  The cache hit ratio of the query.

EXCEPTIONS:

• MilvusClientException

  This exception will be raised when request validation, transport, or server execution fails.

Example

Java

import io.milvus.v2.client.ConnectConfig;
import io.milvus.v2.client.MilvusClientV2;
import io.milvus.v2.service.vector.request.QueryReq;
import io.milvus.v2.service.vector.response.QueryResp;

import java.util.Arrays;
import java.util.concurrent.CompletableFuture;

ConnectConfig connectConfig = ConnectConfig.builder()
        .uri("http://localhost:19530")
        .token("root:Milvus")
        .build();

MilvusClientV2 client = new MilvusClientV2(connectConfig);

CompletableFuture<QueryResp> future = client.queryAsync(QueryReq.builder()
        .collectionName("my_collection")
        .filter("age > 20")
        .outputFields(Arrays.asList("name", "age"))
        .build());
QueryResp response = future.get();