Non-ASCII field names cannot be converted to lower case

[rui-mo]

Bug description

We found that non-ASCII field names could not be converted to lower case due to 'folly::toLowerAscii' only applies to ASCII characters. This causes 'null' output because the characters in 'fileType' are still in upper-case, while 'fieldName' is in lower case (provided by Gluten when isFileColumnNamesReadAsLowerCase is true). 'fileTypeIdx' could not be found and the field is treated as missing column.

E.g. 'Товары' needs to be converted as 'товары', '国Ⅵ' -> '国ⅵ'. To solve this issue, perhaps a library handles UTF-8 characters like 'boost::locale::to_lower' could be used instead.

velox/velox/dwio/parquet/reader/ParquetReader.cpp

Lines 760 to 762 in 3a1a60a

	if (fileColumnNamesReadAsLowerCase) {
	folly::toLowerAscii(childName);
	}

velox/velox/connectors/hive/SplitReader.cpp

Lines 371 to 378 in 3a1a60a

	auto fileTypeIdx = fileType->getChildIdxIfExists(fieldName);
	if (!fileTypeIdx.has_value()) {
	// Column is missing. Most likely due to schema evolution.
	VELOX_CHECK(tableSchema);
	childSpec->setConstantValue(BaseVector::createNullConstant(
	tableSchema->findChild(fieldName),
	1,
	connectorQueryCtx_->memoryPool()));

System information

Velox System Info v0.0.2
CMake Version: 3.28.3
System: Linux-5.4.0-189-generic
Arch: x86_64
C++ Compiler: /usr/bin/c++
C++ Compiler Version: 11.1.0
C Compiler: /usr/bin/cc
C Compiler Version: 11.1.0
CMake Prefix Path: /usr/local;/usr;/;/usr/local/lib/python3.8/dist-packages/cmake/data;/usr/local;/usr/X11R6;/usr/pkg;/opt

Relevant logs

No response