Add alloc_size member function to cudf::column and cudf::table

cpp/include/cudf/column/column.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -279,6 +279,17 @@ class column {
    */
   contents release() noexcept;
 
+  /**
+   * @brief Returns the total device allocation size of the column in bytes
+   *
+   * This includes the size of the data buffer, null mask, and any child columns.
+   * It also includes any padding bytes and is not guaranteed to be the same as
+   * the size()*sizeof(T) for the column's logical type.
+   *
+   * @return The total allocation size in bytes
+   */
+  [[nodiscard]] std::size_t alloc_size() const;
+
   /**
    * @brief Creates an immutable, non-owning view of the column's data and
    * children.

cpp/include/cudf/table/table.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -92,6 +92,15 @@ class table {
    */
   [[nodiscard]] size_type num_rows() const noexcept { return _num_rows; }
 
+  /**
+   * @brief Returns the total device allocation size of the table's columns in bytes
+   *
+   * @see cudf::column::alloc_size
+   *
+   * @return The total allocation size in bytes
+   */
+  [[nodiscard]] std::size_t alloc_size() const;
+
   /**
    * @brief Returns an immutable, non-owning `table_view` of the contents of
    *this `table`.

cpp/src/column/column.cu

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -85,6 +85,15 @@ column::contents column::release() noexcept
                           std::move(_children)};
 }
 
+std::size_t column::alloc_size() const
+{
+  return _data.size() + _null_mask.size() +
+         std::accumulate(
+           _children.begin(), _children.end(), 0, [](auto const& sum, auto const& child) {
+             return sum + child->alloc_size();
+           });
+}
+
 // Create immutable view
 column_view column::view() const
 {

cpp/src/table/table.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@
 
 #include <rmm/cuda_stream_view.hpp>
 
+#include <numeric>
+
 namespace cudf {
 
 // Copy the columns from another table
@@ -61,6 +63,13 @@ table::table(table_view view, rmm::cuda_stream_view stream, rmm::device_async_re
   }
 }
 
+std::size_t table::alloc_size() const
+{
+  return std::accumulate(_columns.begin(), _columns.end(), 0, [](auto const& sum, auto const& c) {
+    return sum + c->alloc_size();
+  });
+}
+
 // Create immutable view
 table_view table::view() const
 {

cpp/tests/table/table_tests.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -148,4 +148,30 @@ TEST_F(TableTest, CreateFromViewVectorEmptyTables)
   EXPECT_EQ(final_view.num_columns(), 0);
 }
 
+TEST_F(TableTest, AllocSize)
+{
+  column_wrapper<int32_t> col1{{1, 2, 3, 4}};
+  column_wrapper<int16_t> col2{{1, 2, 3, 4}};
+
+  CVector cols;
+  cols.push_back(col1.release());
+  cols.push_back(col2.release());
+
+  Table t(std::move(cols));
+  EXPECT_EQ(t.alloc_size(), 24);
+}
+
+TEST_F(TableTest, AllocSizeWithNulls)
+{
+  column_wrapper<int32_t> col1{{1, 2, 3, 4}, {1, 0, 1, 0}};
+  column_wrapper<int16_t> col2{{1, 2, 3, 4}, {1, 0, 1, 0}};
+
+  CVector cols;
+  cols.push_back(col1.release());
+  cols.push_back(col2.release());
+
+  Table t(std::move(cols));
+  EXPECT_EQ(t.alloc_size(), 152);  // bitmask has padding
+}
+
 CUDF_TEST_PROGRAM_MAIN()