diff --git a/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/BatchLoads.java b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/BatchLoads.java
index 56bd14318be4..41fbf8e9dfee 100644
--- a/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/BatchLoads.java
+++ b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/BatchLoads.java
@@ -485,7 +485,7 @@ public WriteResult expandUntriggered(PCollection<KV<DestinationT, ElementT>> inp
     // loading.
     PCollectionTuple partitions =
         results
-            .apply("ReifyResults", new ReifyAsIterable<>())
+            .apply("ReifyResults", new CombineAsIterable<>())
             .setCoder(IterableCoder.of(WriteBundlesToFiles.ResultCoder.of(destinationCoder)))
             .apply(
                 "WritePartitionUntriggered",
diff --git a/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/CombineAsIterable.java b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/CombineAsIterable.java
new file mode 100644
index 000000000000..a537f70e9eea
--- /dev/null
+++ b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/CombineAsIterable.java
@@ -0,0 +1,44 @@
+/*
+ * 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 org.apache.beam.sdk.io.gcp.bigquery;
+
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.transforms.GroupByKey;
+import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.ParDo;
+import org.apache.beam.sdk.transforms.Values;
+import org.apache.beam.sdk.values.KV;
+import org.apache.beam.sdk.values.PCollection;
+
+public class CombineAsIterable<T> extends PTransform<PCollection<T>, PCollection<Iterable<T>>> {
+  @Override
+  public PCollection<Iterable<T>> expand(PCollection<T> input) {
+    return input
+        .apply(
+            "assign single key",
+            ParDo.of(
+                new DoFn<T, KV<String, T>>() {
+                  @ProcessElement
+                  public void processElement(@Element T element, OutputReceiver<KV<String, T>> o) {
+                    o.output(KV.of("key", element));
+                  }
+                }))
+        .apply(GroupByKey.create())
+        .apply(Values.create());
+  }
+}