diff --git a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorker.java b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorker.java
index 35d6f1da7..783a079f7 100644
--- a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorker.java
+++ b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorker.java
@@ -245,6 +245,9 @@ class ConnectionWorker implements AutoCloseable {
   private final RequestProfiler.RequestProfilerHook requestProfilerHook;
   private final TelemetryMetrics telemetryMetrics;
 
+  /** Indicate whether this connection is created during multiplexing mode. */
+  private final Boolean isMultiplexing;
+
   private static String projectMatching = "projects/[^/]+/";
   private static Pattern streamPatternProject = Pattern.compile(projectMatching);
 
@@ -327,7 +330,8 @@ public ConnectionWorker(
       BigQueryWriteSettings clientSettings,
       RetrySettings retrySettings,
       boolean enableRequestProfiler,
-      boolean enableOpenTelemetry)
+      boolean enableOpenTelemetry,
+      boolean isMultiplexing)
       throws IOException {
     this.lock = new ReentrantLock();
     this.hasMessageInWaitingQueue = lock.newCondition();
@@ -353,6 +357,7 @@ public ConnectionWorker(
     this.requestProfilerHook = new RequestProfiler.RequestProfilerHook(enableRequestProfiler);
     this.telemetryMetrics =
         new TelemetryMetrics(this, enableOpenTelemetry, getTableName(), writerId, traceId);
+    this.isMultiplexing = isMultiplexing;
 
     // Always recreate a client for connection worker.
     HashMap<String, String> newHeaders = new HashMap<>();
@@ -744,8 +749,6 @@ private void appendLoop() {
     // Indicate whether we are at the first request after switching destination.
     // True means the schema and other metadata are needed.
     boolean firstRequestForTableOrSchemaSwitch = true;
-    // Represent whether we have entered multiplexing.
-    boolean isMultiplexing = false;
 
     while (!waitingQueueDrained()) {
       this.lock.lock();
@@ -848,7 +851,6 @@ private void appendLoop() {
           streamName = originalRequest.getWriteStream();
           telemetryMetrics.refreshOpenTelemetryTableNameAttributes(getTableName());
           writerSchema = originalRequest.getProtoRows().getWriterSchema();
-          isMultiplexing = true;
           firstRequestForTableOrSchemaSwitch = true;
         }
 
diff --git a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java
index 40d4481e8..8550e553d 100644
--- a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java
+++ b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java
@@ -413,7 +413,8 @@ private ConnectionWorker createConnectionWorker(
             clientSettings,
             retrySettings,
             enableRequestProfiler,
-            enableOpenTelemetry);
+            enableOpenTelemetry,
+            /*isMultiplexing=*/ true);
     connectionWorkerPool.add(connectionWorker);
     log.info(
         String.format(
diff --git a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/StreamWriter.java b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/StreamWriter.java
index a4223adb6..2e5c5881c 100644
--- a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/StreamWriter.java
+++ b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/StreamWriter.java
@@ -256,7 +256,8 @@ private StreamWriter(Builder builder) throws IOException {
                   clientSettings,
                   builder.retrySettings,
                   builder.enableRequestProfiler,
-                  builder.enableOpenTelemetry));
+                  builder.enableOpenTelemetry,
+                  /*isMultiplexing=*/ false));
     } else {
       if (!isDefaultStream(streamName)) {
         log.warning(
diff --git a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerTest.java b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerTest.java
index 2e540d7b2..8c6c8ae81 100644
--- a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerTest.java
+++ b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerTest.java
@@ -87,7 +87,7 @@ public void setUp() throws Exception {
 
   @Test
   public void testMultiplexedAppendSuccess() throws Exception {
-    try (ConnectionWorker connectionWorker = createConnectionWorker()) {
+    try (ConnectionWorker connectionWorker = createMultiplexedConnectionWorker()) {
       long appendCount = 20;
       for (long i = 0; i < appendCount; i++) {
         testBigQueryWrite.addResponse(createAppendResponse(i));
@@ -150,7 +150,7 @@ public void testMultiplexedAppendSuccess() throws Exception {
 
         // We will get the request as the pattern of:
         // (writer_stream: t1, schema: t1)
-        // (writer_stream: _, schema: _)
+        // (writer_stream: t1, schema: _)
         // (writer_stream: t2, schema: t2) -> multiplexing entered.
         // (writer_stream: t2, schema: _)
         // (writer_stream: t1, schema: t1)
@@ -164,11 +164,7 @@ public void testMultiplexedAppendSuccess() throws Exception {
             break;
           case 1:
             // The write stream is empty until we enter multiplexing.
-            if (i == 1) {
-              assertThat(serverRequest.getWriteStream()).isEmpty();
-            } else {
-              assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
-            }
+            assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
             // Schema is empty if not at the first request after table switch.
             assertThat(serverRequest.getProtoRows().hasWriterSchema()).isFalse();
             break;
@@ -198,7 +194,7 @@ public void testMultiplexedAppendSuccess() throws Exception {
 
   @Test
   public void testAppendInSameStream_switchSchema() throws Exception {
-    try (ConnectionWorker connectionWorker = createConnectionWorker()) {
+    try (ConnectionWorker connectionWorker = createMultiplexedConnectionWorker()) {
       long appendCount = 20;
       for (long i = 0; i < appendCount; i++) {
         testBigQueryWrite.addResponse(createAppendResponse(i));
@@ -279,26 +275,20 @@ public void testAppendInSameStream_switchSchema() throws Exception {
 
         // We will get the request as the pattern of:
         // (writer_stream: t1, schema: schema1)
-        // (writer_stream: _, schema: _)
+        // (writer_stream: t1, schema: _)
         // (writer_stream: t1, schema: schema3)
         // (writer_stream: t1, schema: _)
         // (writer_stream: t1, schema: schema1)
         // (writer_stream: t1, schema: _)
         switch (i % 4) {
           case 0:
-            if (i == 0) {
-              assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
-            }
+            assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
             assertThat(
                     serverRequest.getProtoRows().getWriterSchema().getProtoDescriptor().getName())
                 .isEqualTo("foo");
             break;
           case 1:
-            if (i == 1) {
-              assertThat(serverRequest.getWriteStream()).isEmpty();
-            } else {
-              assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
-            }
+            assertThat(serverRequest.getWriteStream()).isEqualTo(TEST_STREAM_1);
             // Schema is empty if not at the first request after table switch.
             assertThat(serverRequest.getProtoRows().hasWriterSchema()).isFalse();
             break;
@@ -346,7 +336,8 @@ public void testAppendButInflightQueueFull() throws Exception {
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing=*/ false);
     testBigQueryWrite.setResponseSleep(org.threeten.bp.Duration.ofSeconds(1));
     ConnectionWorker.setMaxInflightQueueWaitTime(500);
 
@@ -405,7 +396,8 @@ public void testThrowExceptionWhileWithinAppendLoop() throws Exception {
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing=*/ true);
     testBigQueryWrite.setResponseSleep(org.threeten.bp.Duration.ofSeconds(1));
     ConnectionWorker.setMaxInflightQueueWaitTime(500);
 
@@ -476,7 +468,8 @@ public void testLocationMismatch() throws Exception {
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing=*/ true);
     StatusRuntimeException ex =
         assertThrows(
             StatusRuntimeException.class,
@@ -510,7 +503,8 @@ public void testStreamNameMismatch() throws Exception {
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing=*/ true);
     StatusRuntimeException ex =
         assertThrows(
             StatusRuntimeException.class,
@@ -539,13 +533,13 @@ private AppendRowsResponse createAppendResponse(long offset) {
         .build();
   }
 
-  private ConnectionWorker createConnectionWorker() throws IOException {
+  private ConnectionWorker createMultiplexedConnectionWorker() throws IOException {
     // By default use only the first table as table reference.
-    return createConnectionWorker(
+    return createMultiplexedConnectionWorker(
         TEST_STREAM_1, TEST_TRACE_ID, 100, 1000, java.time.Duration.ofSeconds(5));
   }
 
-  private ConnectionWorker createConnectionWorker(
+  private ConnectionWorker createMultiplexedConnectionWorker(
       String streamName,
       String traceId,
       long maxRequests,
@@ -565,7 +559,8 @@ private ConnectionWorker createConnectionWorker(
         client.getSettings(),
         retrySettings,
         /*enableRequestProfiler=*/ false,
-        /*enableOpenTelemetry=*/ false);
+        /*enableOpenTelemetry=*/ false,
+        /*isMultiplexing=*/ true);
   }
 
   private ProtoSchema createProtoSchema(String protoName) {
@@ -663,7 +658,8 @@ public void testThrowExceptionWhileWithinAppendLoop_MaxWaitTimeExceed() throws E
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing*/ false);
     org.threeten.bp.Duration durationSleep = org.threeten.bp.Duration.ofSeconds(2);
     testBigQueryWrite.setResponseSleep(durationSleep);
 
@@ -740,7 +736,8 @@ public void testLongTimeIdleWontFail() throws Exception {
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ false);
+            /*enableOpenTelemetry=*/ false,
+            /*isMultiplexing*/ false);
 
     long appendCount = 10;
     for (int i = 0; i < appendCount * 2; i++) {
@@ -787,7 +784,8 @@ private void exerciseOpenTelemetryAttributesWithStreamNames(String streamName, S
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ true);
+            /*enableOpenTelemetry=*/ true,
+            /*isMultiplexing*/ false);
 
     Attributes attributes = connectionWorker.getTelemetryAttributes();
     String attributesTableId = attributes.get(TelemetryMetrics.telemetryKeyTableId);
@@ -829,7 +827,8 @@ void exerciseOpenTelemetryAttributesWithTraceId(
             client.getSettings(),
             retrySettings,
             /*enableRequestProfiler=*/ false,
-            /*enableOpenTelemetry=*/ true);
+            /*enableOpenTelemetry=*/ true,
+            /*isMultiplexing*/ false);
 
     Attributes attributes = connectionWorker.getTelemetryAttributes();
     checkOpenTelemetryTraceIdAttribute(attributes, 0, expectedField1);
diff --git a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/StreamWriterTest.java b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/StreamWriterTest.java
index 8468fb712..027dd3f15 100644
--- a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/StreamWriterTest.java
+++ b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/StreamWriterTest.java
@@ -949,11 +949,7 @@ public void testProtoSchemaPiping_multiplexingCase() throws Exception {
         assertEquals(
             appendRowsRequest.getProtoRows().getWriterSchema(), ProtoSchema.getDefaultInstance());
         // Before entering multiplexing (i == 1) case, the write stream won't be populated.
-        if (i == 1) {
-          assertEquals(appendRowsRequest.getWriteStream(), "");
-        } else {
-          assertEquals(appendRowsRequest.getWriteStream(), TEST_STREAM_1);
-        }
+        assertEquals(appendRowsRequest.getWriteStream(), TEST_STREAM_1);
       } else if (i % 4 == 2) {
         assertEquals(appendRowsRequest.getProtoRows().getWriterSchema(), schema2);
         assertEquals(appendRowsRequest.getWriteStream(), TEST_STREAM_2);