fix(spanner): transaction_tag should be set on BeginTransactionRequest (#13463)

olavloite · web-flow · commit a429aea4d213 · 2025-12-10T16:20:26.000Z
When using multiplexed sessions, the transaction_tag should also be set on the BeginTransactionRequest.
diff --git a/spanner/client_test.go b/spanner/client_test.go
@@ -6319,6 +6319,26 @@ func TestClient_ReadWriteTransactionWithTag_AbortedOnce(t *testing.T) {
 	if g != w {
 		t.Fatalf("mutations count mismatch\nGot:  %v\nWant: %v", g, w)
 	}
+	// Verify that the BeginTransaction requests also contain the transaction tag.
+	// This is required when using multiplexed sessions.
+	for _, index := range []int{1, 3, 5} {
+		beginReq, ok := requests[index].(*sppb.BeginTransactionRequest)
+		if !ok {
+			t.Fatalf("%d is not a BeginTransactionRequest", index)
+		}
+		if beginReq.RequestOptions == nil {
+			t.Fatalf("%d has no RequestOptions", index)
+		}
+		var want string
+		if index < 5 {
+			want = "test-tag1"
+		} else {
+			want = "test-tag2"
+		}
+		if g, w := beginReq.RequestOptions.TransactionTag, want; g != w {
+			t.Fatalf("%d: transaction tag mismatch\n Got: %v\nWant: %v", index, g, w)
+		}
+	}
 }
 
 func TestClient_ReadWriteTransactionWithTag_SessionNotFound(t *testing.T) {
diff --git a/spanner/transaction.go b/spanner/transaction.go
@@ -1730,8 +1730,7 @@ func beginTransaction(ctx context.Context, opts transactionBeginOptions) (transa
 	if opts.multiplexEnabled {
 		readWriteOptions.MultiplexedSessionPreviousTransactionId = opts.previousTx
 	}
-
-	res, err := opts.client.BeginTransaction(ctx, &sppb.BeginTransactionRequest{
+	request := &sppb.BeginTransactionRequest{
 		Session: opts.sessionID,
 		Options: &sppb.TransactionOptions{
 			Mode: &sppb.TransactionOptions_ReadWrite_{
@@ -1741,7 +1740,13 @@ func beginTransaction(ctx context.Context, opts transactionBeginOptions) (transa
 			IsolationLevel:              opts.txOptions.IsolationLevel,
 		},
 		MutationKey: opts.mutation,
-	})
+	}
+	// When using multiplexed sessions, the BeginTransaction request must include the transaction tag (if any).
+	if opts.multiplexEnabled && opts.txOptions.TransactionTag != "" {
+		request.RequestOptions = &sppb.RequestOptions{TransactionTag: opts.txOptions.TransactionTag}
+	}
+
+	res, err := opts.client.BeginTransaction(ctx, request)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/spanner/transaction_test.go b/spanner/transaction_test.go
@@ -206,19 +206,27 @@ func TestApply_RetryOnAbort(t *testing.T) {
 		Insert("Accounts", []string{"AccountId"}, []interface{}{int64(1)}),
 	}
 
-	if _, e := client.Apply(ctx, ms); e != nil {
+	if _, e := client.Apply(ctx, ms, TransactionTag("my_tag")); e != nil {
 		t.Fatalf("ReadWriteTransaction retry on abort, got %v, want nil.", e)
 	}
 
-	if _, err := shouldHaveReceived(server.TestSpanner, []interface{}{
+	if reqs, err := shouldHaveReceived(server.TestSpanner, []interface{}{
 		&sppb.BatchCreateSessionsRequest{},
 		&sppb.BeginTransactionRequest{},
 		&sppb.CommitRequest{}, // First commit fails.
 		&sppb.BeginTransactionRequest{},
 		&sppb.CommitRequest{}, // Second commit succeeds.
 	}); err != nil {
 		t.Fatal(err)
+	} else {
+		if g, w := reqs[1].(*sppb.BeginTransactionRequest).RequestOptions.TransactionTag, "my_tag"; g != w {
+			t.Fatalf("transaction tag mismatch\n Got: %v\nWant: %v", g, w)
+		}
+		if g, w := reqs[3].(*sppb.BeginTransactionRequest).RequestOptions.TransactionTag, "my_tag"; g != w {
+			t.Fatalf("transaction tag mismatch\n Got: %v\nWant: %v", g, w)
+		}
 	}
+
 }
 
 // Tests that SessionNotFound errors are retried.
