table revision number

common/proto/tables_data.proto

@@ -199,6 +199,9 @@ message StageTableDataImportRequest {
   string import_id = 1;
   string table_name = 2;
   repeated TableDataImportRow rows = 3;
+  // Import-contract revision returned by GetTableImportDescriptor. A zero
+  // value is accepted for older clients and snapshots the current revision.
+  int64 expected_table_revision = 4;
 }
 
 message TableDataImportRow {