Fix incorrect downcast in ReserveData for string types

1 files changed, 6 insertions, 5 deletions

diff --git a/ydb/core/formats/arrow/arrow_helpers.cpp b/ydb/core/formats/arrow/arrow_helpers.cpp
index fbad4b2d1c..c4a86ed5f0 100644
--- a/ydb/core/formats/arrow/arrow_helpers.cpp
+++ b/ydb/core/formats/arrow/arrow_helpers.cpp
@@ -798,11 +798,12 @@ bool ArrayScalarsEqual(const std::shared_ptr<arrow::Array>& lhs, const std::shar
 
 bool ReserveData(arrow::ArrayBuilder& builder, const size_t size) {
     arrow::Status result = arrow::Status::OK();
-    if (builder.type()->id() == arrow::Type::BINARY) {
-        arrow::BaseBinaryBuilder<arrow::BinaryType>& bBuilder = static_cast<arrow::BaseBinaryBuilder<arrow::BinaryType>&>(builder);
-        result = bBuilder.ReserveData(size);
-    } else if (builder.type()->id() == arrow::Type::STRING) {
-        arrow::BaseBinaryBuilder<arrow::StringType>& bBuilder = static_cast<arrow::BaseBinaryBuilder<arrow::StringType>&>(builder);
+    if (builder.type()->id() == arrow::Type::BINARY ||
+        builder.type()->id() == arrow::Type::STRING)
+    {
+        static_assert(std::is_convertible_v<arrow::StringBuilder&, arrow::BaseBinaryBuilder<arrow::BinaryType>&>,
+            "Expected StringBuilder to be BaseBinaryBuilder<BinaryType>");
+        auto& bBuilder = static_cast<arrow::BaseBinaryBuilder<arrow::BinaryType>&>(builder);
         result = bBuilder.ReserveData(size);
     }