from_json: null only schema-mismatched rows

src/main/cpp/benchmarks/CMakeLists.txt

@@ -1,5 +1,5 @@
 #=============================================================================
-# Copyright (c) 2022-2025, NVIDIA CORPORATION.
+# Copyright (c) 2022-2026, NVIDIA CORPORATION.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -84,5 +84,8 @@ ConfigureBench(BLOOM_FILTER_BENCH
 ConfigureBench(GET_JSON_OBJECT_BENCH
   get_json_object.cu)
 
+ConfigureBench(FROM_JSON_TO_STRUCTS_BENCH
+  from_json_to_structs.cu)
+
 ConfigureBench(PARSE_URI_BENCH
   parse_uri.cpp)

src/main/cpp/benchmarks/from_json_to_structs.cu

@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2026, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cudf_test/column_wrapper.hpp>
+
+#include <cudf/strings/strings_column_view.hpp>
+#include <cudf/types.hpp>
+
+#include <json_utils.hpp>
+#include <nvbench/nvbench.cuh>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace {
+
+std::unique_ptr<cudf::column> make_input(cudf::size_type num_rows, cudf::size_type mismatch_percent)
+{
+  std::string const valid      = R"({"data":{"c2":[{"c3":19,"c4":"x"}],"c1":1},"id":10})";
+  std::string const mismatched = R"({"data":{"c2":[19],"c1":2},"id":20})";
+
+  std::vector<std::string> rows;
+  rows.reserve(num_rows);
+  for (cudf::size_type row = 0; row < num_rows; ++row) {
+    rows.push_back(mismatch_percent > 0 && row % 100 < mismatch_percent ? mismatched : valid);
+  }
+  return cudf::test::strings_column_wrapper(rows.begin(), rows.end()).release();
+}
+
+std::vector<std::string> nested_schema_names()
+{
+  return {"data", "c1", "c2", "element", "c3", "c4", "id"};
+}
+
+std::vector<int> nested_schema_num_children() { return {2, 0, 1, 2, 0, 0, 0}; }
+
+std::vector<int> nested_schema_types()
+{
+  return {static_cast<int>(cudf::type_id::STRUCT),
+          static_cast<int>(cudf::type_id::INT32),
+          static_cast<int>(cudf::type_id::LIST),
+          static_cast<int>(cudf::type_id::STRUCT),
+          static_cast<int>(cudf::type_id::INT32),
+          static_cast<int>(cudf::type_id::STRING),
+          static_cast<int>(cudf::type_id::INT32)};
+}
+
+std::vector<int> nested_schema_scales() { return {0, 0, 0, 0, 0, 0, 0}; }
+
+std::vector<int> nested_schema_precisions() { return {-1, -1, -1, -1, -1, -1, -1}; }
+
+}  // namespace
+
+void BM_from_json_to_structs(nvbench::state& state)
+{
+  auto const num_rows         = static_cast<cudf::size_type>(state.get_int64("num_rows"));
+  auto const mismatch_percent = static_cast<cudf::size_type>(state.get_int64("mismatch_percent"));
+  auto const input            = make_input(num_rows, mismatch_percent);
+
+  auto const col_names    = nested_schema_names();
+  auto const num_children = nested_schema_num_children();
+  auto const types        = nested_schema_types();
+  auto const scales       = nested_schema_scales();
+  auto const precisions   = nested_schema_precisions();
+
+  state.exec(nvbench::exec_tag::sync, [&](nvbench::launch& launch) {
+    auto output = spark_rapids_jni::from_json_to_structs(cudf::strings_column_view{input->view()},
+                                                         col_names,
+                                                         num_children,
+                                                         types,
+                                                         scales,
+                                                         precisions,
+                                                         true,
+                                                         true,
+                                                         true,
+                                                         true,
+                                                         true);
+  });
+
+  state.add_buffer_size(num_rows, "rows", "Rows");
+}
+
+NVBENCH_BENCH(BM_from_json_to_structs)
+  .set_name("from_json_to_structs")
+  .add_int64_axis("num_rows", {10000, 100000})
+  .add_int64_axis("mismatch_percent", {0, 1});

src/main/cpp/src/from_json_to_structs.cu

@@ -21,14 +21,17 @@
 
 #include <cudf/column/column_device_view.cuh>
 #include <cudf/column/column_factories.hpp>
+#include <cudf/copying.hpp>
 #include <cudf/detail/iterator.cuh>
 #include <cudf/detail/utilities/cuda.cuh>
+#include <cudf/detail/utilities/vector_factories.hpp>
 #include <cudf/detail/valid_if.cuh>
 #include <cudf/io/json.hpp>
 #include <cudf/lists/lists_column_view.hpp>
 #include <cudf/null_mask.hpp>
 #include <cudf/strings/detail/strings_children.cuh>
 #include <cudf/strings/strings_column_view.hpp>
+#include <cudf/utilities/bit.hpp>
 #include <cudf/utilities/traits.hpp>
 
 #include <rmm/cuda_stream_view.hpp>
@@ -48,6 +51,9 @@
 #include <thrust/transform.h>
 #include <thrust/uninitialized_fill.h>
 
+#include <algorithm>
+#include <map>
+
 namespace spark_rapids_jni {
 
 namespace detail {
@@ -142,6 +148,80 @@ std::pair<cudf::io::schema_element, schema_element_with_precision> generate_stru
       cudf::data_type{cudf::type_id::STRUCT}, -1, std::move(schema_cols_with_precisions)}};
 }
 
+void nullify_rows(cudf::column& input,
+                  std::vector<cudf::size_type> const& row_indices,
+                  rmm::cuda_stream_view stream,
+                  rmm::device_async_resource_ref mr)
+{
+  if (row_indices.empty()) { return; }
+
+  auto const input_view = input.view();
+  for (auto const row : row_indices) {
+    CUDF_EXPECTS(row >= 0 && row < input_view.size(), "Schema mismatch row index out of bounds.");
+  }
+
+  auto null_mask =
+    input_view.nullable()
+      ? cudf::copy_bitmask(input_view, stream, mr)
+      : cudf::create_null_mask(input_view.size(), cudf::mask_state::ALL_VALID, stream, mr);
+  auto d_row_indices = cudf::detail::make_device_uvector_async(row_indices, stream, mr);
+
+  auto mask_ptr = static_cast<cudf::bitmask_type*>(null_mask.data());
+  thrust::for_each(rmm::exec_policy_nosync(stream),
+                   d_row_indices.begin(),
+                   d_row_indices.end(),
+                   [mask_ptr] __device__(auto const row) { cudf::clear_bit(mask_ptr, row); });
+
+  auto const null_count = cudf::null_count(
+    static_cast<cudf::bitmask_type const*>(null_mask.data()), 0, input_view.size(), stream);
+  input.set_null_mask(std::move(null_mask), null_count);
+}
+
+std::unique_ptr<cudf::column> make_lists_column_with_null_sanitization(
+  cudf::size_type num_rows,
+  std::unique_ptr<cudf::column> offsets_column,
+  std::unique_ptr<cudf::column> child_column,
+  cudf::size_type null_count,
+  rmm::device_buffer&& null_mask,
+  rmm::cuda_stream_view stream,
+  rmm::device_async_resource_ref mr)
+{
+  std::vector<std::unique_ptr<cudf::column>> children;
+  children.emplace_back(std::move(offsets_column));
+  children.emplace_back(std::move(child_column));
+  auto output = std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::LIST},
+                                               num_rows,
+                                               rmm::device_buffer{},
+                                               std::move(null_mask),
+                                               null_count,
+                                               std::move(children));
+  // Row-level schema mismatch nulls can leave child data under null parents; sanitize it here.
+  if (null_count > 0) { output = cudf::purge_nonempty_nulls(output->view(), stream, mr); }
+  return output;
+}
+
+std::unique_ptr<cudf::column> make_structs_column_with_null_consistency(
+  cudf::size_type num_rows,
+  std::vector<std::unique_ptr<cudf::column>>&& children,
+  cudf::size_type null_count,
+  rmm::device_buffer&& null_mask,
+  rmm::cuda_stream_view stream,
+  rmm::device_async_resource_ref mr)
+{
+  if (null_count > 0) {
+    // make_structs_column superimposes parent nulls onto children for a consistent nested column.
+    return cudf::make_structs_column(
+      num_rows, std::move(children), null_count, std::move(null_mask), stream, mr);
+  }
+
+  return std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::STRUCT},
+                                        num_rows,
+                                        rmm::device_buffer{},
+                                        std::move(null_mask),
+                                        null_count,
+                                        std::move(children));
+}
+
 using string_index_pair = cuda::std::pair<char const*, cudf::size_type>;
 
 std::unique_ptr<cudf::column> cast_strings_to_booleans(cudf::column_view const& input,
@@ -711,14 +791,14 @@ std::unique_ptr<cudf::column> convert_data_type(InputType&& input,
       new_children.emplace_back(convert_data_type(
         std::move(child), child_schema, allow_nonnumeric_numbers, is_us_locale, stream, mr));
 
-      // Do not use `cudf::make_lists_column` since we do not need to call `purge_nonempty_nulls`
-      // on the child column as it does not have non-empty nulls.
-      return std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::LIST},
-                                            num_rows,
-                                            rmm::device_buffer{},
-                                            std::move(*input_content.null_mask),
-                                            null_count,
-                                            std::move(new_children));
+      return make_lists_column_with_null_sanitization(
+        num_rows,
+        std::move(new_children[cudf::lists_column_view::offsets_column_index]),
+        std::move(new_children[cudf::lists_column_view::child_column_index]),
+        null_count,
+        std::move(*input_content.null_mask),
+        stream,
+        mr);
     }
 
     if (schema.type.id() == cudf::type_id::STRUCT) {
@@ -733,14 +813,12 @@ std::unique_ptr<cudf::column> convert_data_type(InputType&& input,
                                                     mr));
       }
 
-      // Do not use `cudf::make_structs_column` since we do not need to call `superimpose_nulls`
-      // on the children columns.
-      return std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::STRUCT},
-                                            num_rows,
-                                            rmm::device_buffer{},
-                                            std::move(*input_content.null_mask),
-                                            null_count,
-                                            std::move(new_children));
+      return make_structs_column_with_null_consistency(num_rows,
+                                                       std::move(new_children),
+                                                       null_count,
+                                                       std::move(*input_content.null_mask),
+                                                       stream,
+                                                       mr);
     }
   } else {  // input_is_const_cv
     auto const null_count   = input.null_count();
@@ -761,14 +839,14 @@ std::unique_ptr<cudf::column> convert_data_type(InputType&& input,
       new_children.emplace_back(
         convert_data_type(child, child_schema, allow_nonnumeric_numbers, is_us_locale, stream, mr));
 
-      // Do not use `cudf::make_lists_column` since we do not need to call `purge_nonempty_nulls`
-      // on the child column as it does not have non-empty nulls.
-      return std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::LIST},
-                                            num_rows,
-                                            rmm::device_buffer{},
-                                            cudf::copy_bitmask(input, stream, mr),
-                                            null_count,
-                                            std::move(new_children));
+      return make_lists_column_with_null_sanitization(
+        num_rows,
+        std::move(new_children[cudf::lists_column_view::offsets_column_index]),
+        std::move(new_children[cudf::lists_column_view::child_column_index]),
+        null_count,
+        cudf::copy_bitmask(input, stream, mr),
+        stream,
+        mr);
     }
 
     if (schema.type.id() == cudf::type_id::STRUCT) {
@@ -783,14 +861,12 @@ std::unique_ptr<cudf::column> convert_data_type(InputType&& input,
                                                     mr));
       }
 
-      // Do not use `cudf::make_structs_column` since we do not need to call `superimpose_nulls`
-      // on the children columns.
-      return std::make_unique<cudf::column>(cudf::data_type{cudf::type_id::STRUCT},
-                                            num_rows,
-                                            rmm::device_buffer{},
-                                            cudf::copy_bitmask(input, stream, mr),
-                                            null_count,
-                                            std::move(new_children));
+      return make_structs_column_with_null_consistency(num_rows,
+                                                       std::move(new_children),
+                                                       null_count,
+                                                       cudf::copy_bitmask(input, stream, mr),
+                                                       stream,
+                                                       mr);
     }
   }
 
@@ -838,9 +914,9 @@ std::unique_ptr<cudf::column> from_json_to_structs(cudf::strings_column_view con
       .dtypes(schema)
       .prune_columns(schema.child_types.size() != 0);
 
-  auto const parsed_table_with_meta = cudf::io::read_json(opts_builder.build());
-  auto const& parsed_meta           = parsed_table_with_meta.metadata;
-  auto parsed_columns               = parsed_table_with_meta.tbl->release();
+  auto parsed_result = cudf::io::read_json_with_row_diagnostics(opts_builder.build(), stream, mr);
+  auto const& parsed_meta = parsed_result.data.metadata;
+  auto parsed_columns     = parsed_result.data.tbl->release();
 
   CUDF_EXPECTS(parsed_columns.size() == schema.child_types.size(),
                "Numbers of output columns is different from schema size.");
@@ -855,6 +931,14 @@ std::unique_ptr<cudf::column> from_json_to_structs(cudf::strings_column_view con
 
     auto const& [col_name, col_schema] = schema_with_precision.child_types[i];
     CUDF_EXPECTS(parsed_meta.schema_info[i].name == col_name, "Mismatched column name.");
+    auto const mismatch_rows =
+      std::find_if(parsed_result.diagnostics.top_level_columns_with_schema_mismatch_rows.begin(),
+                   parsed_result.diagnostics.top_level_columns_with_schema_mismatch_rows.end(),
+                   [&col_name](auto const& row_info) { return row_info.column_name == col_name; });
+    if (mismatch_rows !=
+        parsed_result.diagnostics.top_level_columns_with_schema_mismatch_rows.end()) {
+      nullify_rows(*parsed_columns[i], mismatch_rows->row_indices, stream, mr);
+    }
     converted_cols.emplace_back(convert_data_type(std::move(parsed_columns[i]),
                                                   col_schema,
                                                   allow_nonnumeric_numbers,
@@ -867,15 +951,13 @@ std::unique_ptr<cudf::column> from_json_to_structs(cudf::strings_column_view con
   auto [null_mask, null_count] = cudf::detail::valid_if(
     valid_it, valid_it + should_be_nullified->size(), thrust::logical_not<bool>{}, stream, mr);
 
-  // Do not use `cudf::make_structs_column` since we do not need to call `superimpose_nulls`
-  // on the children columns.
-  return std::make_unique<cudf::column>(
-    cudf::data_type{cudf::type_id::STRUCT},
+  return make_structs_column_with_null_consistency(
     input.size(),
-    rmm::device_buffer{},
-    null_count > 0 ? std::move(null_mask) : rmm::device_buffer{0, stream, mr},
+    std::move(converted_cols),
     null_count,
-    std::move(converted_cols));
+    null_count > 0 ? std::move(null_mask) : rmm::device_buffer{0, stream, mr},
+    stream,
+    mr);
 }
 
 }  // namespace