Add TruncateCollection API to Java SDK

sdk-core/src/main/java/io/milvus/v2/client/MilvusClientV2.java

@@ -411,6 +411,15 @@ public void dropCollection(DropCollectionReq request) {
         vectorService.removeCollectionCache(request.getDatabaseName(), request.getCollectionName());
     }
 
+    /**
+     * Truncates a collection in Milvus, removing all data while preserving the collection schema.
+     *
+     * @param request truncate collection request
+     */
+    public void truncateCollection(TruncateCollectionReq request) {
+        rpcUtils.retry(() -> collectionService.truncateCollection(this.getRpcStub(), request));
+    }
+
     /**
      * Alter a collection in Milvus.
      * Deprecated, replaced by alterCollectionProperties from SDK v2.5.3, to keep consistence with other SDKs

sdk-core/src/main/java/io/milvus/v2/service/collection/CollectionService.java

@@ -238,6 +238,24 @@ public Void dropCollection(MilvusServiceGrpc.MilvusServiceBlockingStub blockingS
         return null;
     }
 
+    public Void truncateCollection(MilvusServiceGrpc.MilvusServiceBlockingStub blockingStub, TruncateCollectionReq request) {
+        String dbName = request.getDatabaseName();
+        String collectionName = request.getCollectionName();
+        String title = String.format("Truncate collection: '%s' in database: '%s'", collectionName, dbName);
+        TruncateCollectionRequest.Builder builder = TruncateCollectionRequest.newBuilder()
+                .setCollectionName(collectionName);
+        if (StringUtils.isNotEmpty(dbName)) {
+            builder.setDbName(dbName);
+        }
+        Status status = blockingStub.truncateCollection(builder.build()).getStatus();
+        rpcUtils.handleResponse(title, status);
+
+        // remove the last write timestamp since all data has been cleared
+        String key = GTsDict.CombineCollectionName(actualDbName(dbName), collectionName);
+        GTsDict.getInstance().removeCollectionTs(key);
+        return null;
+    }
+
     public Void alterCollectionProperties(MilvusServiceGrpc.MilvusServiceBlockingStub blockingStub, AlterCollectionPropertiesReq request) {
         String dbName = request.getDatabaseName();
         String collectionName = request.getCollectionName();

sdk-core/src/main/java/io/milvus/v2/service/collection/request/TruncateCollectionReq.java

@@ -0,0 +1,82 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.milvus.v2.service.collection.request;
+
+public class TruncateCollectionReq {
+    private String databaseName;
+    private String collectionName;
+
+    private TruncateCollectionReq(TruncateCollectionReqBuilder builder) {
+        this.databaseName = builder.databaseName;
+        this.collectionName = builder.collectionName;
+    }
+
+    public static TruncateCollectionReqBuilder builder() {
+        return new TruncateCollectionReqBuilder();
+    }
+
+    // Getters
+    public String getDatabaseName() {
+        return databaseName;
+    }
+
+    public String getCollectionName() {
+        return collectionName;
+    }
+
+    // Setters
+    public void setDatabaseName(String databaseName) {
+        this.databaseName = databaseName;
+    }
+
+    public void setCollectionName(String collectionName) {
+        this.collectionName = collectionName;
+    }
+
+    @Override
+    public String toString() {
+        return "TruncateCollectionReq{" +
+                "databaseName='" + databaseName + '\'' +
+                ", collectionName='" + collectionName + '\'' +
+                '}';
+    }
+
+    public static class TruncateCollectionReqBuilder {
+        private String databaseName;
+        private String collectionName;
+
+        private TruncateCollectionReqBuilder() {
+        }
+
+        public TruncateCollectionReqBuilder databaseName(String databaseName) {
+            this.databaseName = databaseName;
+            return this;
+        }
+
+        public TruncateCollectionReqBuilder collectionName(String collectionName) {
+            this.collectionName = collectionName;
+            return this;
+        }
+
+        public TruncateCollectionReq build() {
+            return new TruncateCollectionReq(this);
+        }
+    }
+}

sdk-core/src/test/java/io/milvus/server/MockMilvusServerImpl.java

@@ -135,6 +135,21 @@ public void setDropCollectionResponse(io.milvus.grpc.Status resp) {
         respDropCollection = resp;
     }
 
+    private io.milvus.grpc.TruncateCollectionResponse respTruncateCollection;
+
+    @Override
+    public void truncateCollection(io.milvus.grpc.TruncateCollectionRequest request,
+                                   io.grpc.stub.StreamObserver<io.milvus.grpc.TruncateCollectionResponse> responseObserver) {
+        logger.info("MockServer receive truncateCollection() call");
+
+        responseObserver.onNext(respTruncateCollection);
+        responseObserver.onCompleted();
+    }
+
+    public void setTruncateCollectionResponse(io.milvus.grpc.TruncateCollectionResponse resp) {
+        respTruncateCollection = resp;
+    }
+
     @Override
     public void getCollectionStatistics(io.milvus.grpc.GetCollectionStatisticsRequest request,
                                         io.grpc.stub.StreamObserver<io.milvus.grpc.GetCollectionStatisticsResponse> responseObserver) {

sdk-core/src/test/java/io/milvus/v2/BaseTest.java

@@ -111,6 +111,7 @@ public void setUp() {
         when(blockingStub.releaseCollection(any())).thenReturn(successStatus);
         when(blockingStub.getLoadState(any())).thenReturn(GetLoadStateResponse.newBuilder().setState(LoadState.LoadStateLoaded).setStatus(successStatus).build());
         when(blockingStub.dropCollection(any())).thenReturn(successStatus);
+        when(blockingStub.truncateCollection(any())).thenReturn(TruncateCollectionResponse.newBuilder().setStatus(successStatus).build());
         when(blockingStub.hasCollection(any())).thenReturn(trueResponse);
         when(blockingStub.describeCollection(any())).thenReturn(describeCollectionResponse);
         when(blockingStub.renameCollection(any())).thenReturn(successStatus);

sdk-core/src/test/java/io/milvus/v2/service/collection/CollectionTest.java

@@ -140,6 +140,14 @@ void testDropCollection() {
         client_v2.dropCollection(req);
     }
 
+    @Test
+    void testTruncateCollection() {
+        TruncateCollectionReq req = TruncateCollectionReq.builder()
+                .collectionName("test")
+                .build();
+        client_v2.truncateCollection(req);
+    }
+
     @Test
     void testHasCollection() {
         HasCollectionReq req = HasCollectionReq.builder()