feat(bigtable): throw an error if there is a schema change in metadata returned by ExecuteQueryResponse

google/cloud/bigtable/internal/data_connection_impl.cc

@@ -119,10 +119,12 @@ class DefaultPartialResultSetReader
       std::shared_ptr<OperationContext> operation_context,
       std::unique_ptr<internal::StreamingReadRpc<
           google::bigtable::v2::ExecuteQueryResponse>>
-          reader)
+          reader,
+      google::bigtable::v2::ResultSetMetadata initial_metadata)
       : context_(std::move(context)),
         operation_context_(std::move(operation_context)),
-        reader_(std::move(reader)) {}
+        reader_(std::move(reader)),
+        initial_metadata_(std::move(initial_metadata)) {}
 
   ~DefaultPartialResultSetReader() override = default;
 
@@ -148,10 +150,22 @@ class DefaultPartialResultSetReader
         return true;
       }
 
-      // Ignore metadata from the stream because PartialResultSetSource already
-      // has it set (in ExecuteQuery).
-      // TODO(#15701): Investigate expected behavior for processing metadata.
+      // Throw an error when there is a schema difference between
+      // ExecuteQueryResponse and PrepareQueryResponse.
       if (response.has_metadata()) {
+        std::string initial_metadata_str;
+        std::string response_metadata_str;
+        bool metadata_matched =
+            initial_metadata_.SerializeToString(&initial_metadata_str) &&
+            response.metadata().SerializeToString(&response_metadata_str) &&
+            initial_metadata_str == response_metadata_str;
+        if (response.metadata().ByteSizeLong() > 0 && !metadata_matched) {
+          final_status_ = google::cloud::Status(
+              google::cloud::StatusCode::kAborted,
+              "Schema changed during ExecuteQuery operation");
+          operation_context_->PostCall(*context_, final_status_);
+          return false;
+        }
         continue;
       }
 
@@ -173,6 +187,7 @@ class DefaultPartialResultSetReader
   std::unique_ptr<
       internal::StreamingReadRpc<google::bigtable::v2::ExecuteQueryResponse>>
       reader_;
+  google::bigtable::v2::ResultSetMetadata initial_metadata_;
   Status final_status_;
 };
 
@@ -896,8 +911,8 @@ bigtable::RowStream DataConnectionImpl::ExecuteQuery(
           std::shared_ptr<OperationContext> const& operation_context) mutable
       -> StatusOr<std::unique_ptr<bigtable::ResultSourceInterface>> {
     auto factory =
-        [stub, request, tracing_enabled, tracing_options,
-         operation_context](std::string const& resume_token) mutable {
+        [stub, request, tracing_enabled, tracing_options, operation_context,
+         initial_metadata = metadata](std::string const& resume_token) mutable {
           if (!resume_token.empty()) request.set_resume_token(resume_token);
           auto context = std::make_shared<grpc::ClientContext>();
           auto const& options = internal::CurrentOptions();
@@ -906,7 +921,8 @@ bigtable::RowStream DataConnectionImpl::ExecuteQuery(
           auto stream = stub->ExecuteQuery(context, options, request);
           std::unique_ptr<PartialResultSetReader> reader =
               std::make_unique<DefaultPartialResultSetReader>(
-                  std::move(context), operation_context, std::move(stream));
+                  std::move(context), operation_context, std::move(stream),
+                  std::move(initial_metadata));
           if (tracing_enabled) {
             reader = std::make_unique<LoggingResultSetReader>(std::move(reader),
                                                               tracing_options);

google/cloud/bigtable/internal/data_connection_impl_test.cc

@@ -77,6 +77,7 @@ using ::testing::Contains;
 using ::testing::ElementsAre;
 using ::testing::ElementsAreArray;
 using ::testing::Eq;
+using ::testing::HasSubstr;
 using ::testing::Matcher;
 using ::testing::MockFunction;
 using ::testing::Pair;
@@ -3695,6 +3696,92 @@ TEST_F(DataConnectionTest,
   EXPECT_THAT(row2.values().at(1).get<std::string>(), IsOkAndHolds("v2"));
 }
 
+TEST_F(DataConnectionTest, ExecuteQueryFailureWithSchemaChange) {
+  auto factory = std::make_unique<SimpleOperationContextFactory>();
+
+  auto mock = std::make_shared<MockBigtableStub>();
+  auto fake_cq_impl = std::make_shared<FakeCompletionQueueImpl>();
+  auto mock_bg = std::make_unique<MockBackgroundThreads>();
+  EXPECT_CALL(*mock_bg, cq).WillRepeatedly([&]() {
+    return CompletionQueue{fake_cq_impl};
+  });
+  auto constexpr kResultMetadataText = R"pb(
+    proto_schema {
+      columns {
+        name: "row_key"
+        type { string_type {} }
+      }
+      columns {
+        name: "value"
+        type { string_type {} }
+      }
+    }
+  )pb";
+  v2::PrepareQueryResponse pq_response;
+  pq_response.set_prepared_query("test-pq-id-54321");
+  ASSERT_TRUE(google::protobuf::TextFormat::ParseFromString(
+      kResultMetadataText, pq_response.mutable_metadata()));
+  *pq_response.mutable_valid_until() = internal::ToProtoTimestamp(
+      std::chrono::system_clock::now() + std::chrono::seconds(3600));
+
+  auto constexpr kExecuteQueryResultMetadataText = R"pb(
+    proto_schema {
+      columns {
+        name: "row_key"
+        type { string_type {} }
+      }
+      columns {
+        name: "different_value"
+        type { string_type {} }
+      }
+    }
+  )pb";
+  v2::ExecuteQueryResponse eq_response;
+  ASSERT_TRUE(google::protobuf::TextFormat::ParseFromString(
+      kExecuteQueryResultMetadataText, eq_response.mutable_metadata()));
+
+  auto refresh_fn = []() {
+    return make_ready_future(
+        StatusOr<google::bigtable::v2::PrepareQueryResponse>(
+            Status{StatusCode::kUnimplemented, "not implemented"}));
+  };
+  EXPECT_CALL(*mock, ExecuteQuery)
+      .Times(3)
+      .WillRepeatedly(
+          [&](auto, auto const&,
+              google::bigtable::v2::ExecuteQueryRequest const& request) {
+            EXPECT_EQ(request.app_profile_id(), kAppProfile);
+            EXPECT_EQ(request.instance_name(),
+                      "projects/test-project/instances/test-instance");
+            auto stream = std::make_unique<MockExecuteQueryStream>();
+            EXPECT_CALL(*stream, Read)
+                .WillOnce([&](google::bigtable::v2::ExecuteQueryResponse* r) {
+                  *r = eq_response;
+                  return absl::nullopt;
+                });
+            return stream;
+          });
+
+  auto conn = TestConnection(std::move(mock), std::move(factory));
+  internal::OptionsSpan span(CallOptions());
+  Project p("test-project");
+  bigtable::SqlStatement statement("SELECT * FROM the-table");
+  bigtable::InstanceResource instance(p, "test-instance");
+  auto query_plan =
+      QueryPlan::Create(CompletionQueue(fake_cq_impl), std::move(pq_response),
+                        std::move(refresh_fn));
+  auto prepared_query =
+      bigtable::PreparedQuery(instance, statement, std::move(query_plan));
+  auto bq = prepared_query.BindParameters({});
+  bigtable::ExecuteQueryParams params{std::move(bq)};
+  auto row_stream = conn->ExecuteQuery(std::move(params));
+  for (auto const& row : row_stream) {
+    EXPECT_THAT(row,
+                StatusIs(StatusCode::kAborted, HasSubstr("Schema changed")));
+  }
+  fake_cq_impl->SimulateCompletion(false);
+}
+
 }  // namespace
 GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_END
 }  // namespace bigtable_internal