feat: add experimental reverse scan for public preview

Google APIs · copybara-github · commit ae187063e3d8 · 2023-06-26T14:18:08.000-07:00
PiperOrigin-RevId: 543539118
diff --git a/google/bigtable/v2/bigtable.proto b/google/bigtable/v2/bigtable.proto
@@ -271,6 +271,16 @@ message ReadRowsRequest {
 
   // The view into RequestStats, as described above.
   RequestStatsView request_stats_view = 6;
+
+  // Experimental API - Please note that this API is currently experimental
+  // and can change in the future.
+  //
+  // Return rows in lexiographical descending order of the row keys. The row
+  // contents will not be affected by this flag.
+  // Example result set: [
+  // {key: "k2", "f:col1": "v1", "f:col2": "v1"}, {key: "k1", "f:col1": "v2",
+  // "f:col2": "v2"} ].
+  bool reversed = 7;
 }
 
 // Response message for Bigtable.ReadRows.
diff --git a/google/bigtable/v2/feature_flags.proto b/google/bigtable/v2/feature_flags.proto
@@ -33,6 +33,10 @@ option ruby_package = "Google::Cloud::Bigtable::V2";
 // This is an internal implementation detail and should not be used by endusers
 // directly.
 message FeatureFlags {
+  // Notify the server that the client supports reverse scans. The server will
+  // reject ReadRowsRequests with the reverse bit set when this is absent.
+  bool reverse_scans = 1;
+
   // Notify the server that the client enables batch write flow control by
   // requesting RateLimitInfo from MutateRowsResponse.
   bool mutate_rows_rate_limit = 3;
