diff --git a/google/spanner/admin/database/v1/spanner_database_admin.proto b/google/spanner/admin/database/v1/spanner_database_admin.proto
index 084f98c68b..36e06f1e1f 100644
--- a/google/spanner/admin/database/v1/spanner_database_admin.proto
+++ b/google/spanner/admin/database/v1/spanner_database_admin.proto
@@ -813,6 +813,11 @@ message UpdateDatabaseDdlRequest {
   // For more details, see protobuffer [self
   // description](https://developers.google.com/protocol-buffers/docs/techniques#self-description).
   bytes proto_descriptors = 4 [(google.api.field_behavior) = OPTIONAL];
+
+  // Optional. This field is exposed to be used by the Spanner Migration Tool.
+  // For more details, see
+  // [SMT](https://github.com/GoogleCloudPlatform/spanner-migration-tool).
+  bool throughput_mode = 5 [(google.api.field_behavior) = OPTIONAL];
 }
 
 // Action information extracted from a DDL statement. This proto is used to