zclllyybb commented on code in PR #60890:
URL: https://github.com/apache/doris/pull/60890#discussion_r2888489720
##########
be/src/vec/functions/function_string.h:
##########
@@ -178,6 +178,77 @@ class FunctionStrcmp : public IFunction {
}
};
+class FunctionHammingDistance : public IFunction {
+public:
+ static constexpr auto name = "hamming_distance";
+
+ static FunctionPtr create() { return
std::make_shared<FunctionHammingDistance>(); }
+
+ String get_name() const override { return name; }
+
+ size_t get_number_of_arguments() const override { return 2; }
+
+ DataTypePtr get_return_type_impl(const DataTypes& arguments) const
override {
+ return std::make_shared<DataTypeInt64>();
+ }
+
+ Status execute_impl(FunctionContext* context, Block& block, const
ColumnNumbers& arguments,
+ uint32_t result, size_t input_rows_count) const
override {
+ auto left_column =
+
block.get_by_position(arguments[0]).column->convert_to_full_column_if_const();
+ auto right_column =
+
block.get_by_position(arguments[1]).column->convert_to_full_column_if_const();
+
+ const auto* left =
check_and_get_column<ColumnString>(left_column.get());
+ const auto* right =
check_and_get_column<ColumnString>(right_column.get());
+
+ if (left == nullptr || right == nullptr) {
+ return Status::RuntimeError("Illegal column of argument of
function {}", get_name());
+ }
+
+ auto result_column = ColumnInt64::create();
+ auto& result_data = result_column->get_data();
+ result_data.resize(input_rows_count);
+
+ for (size_t i = 0; i < input_rows_count; ++i) {
+ StringRef l = left->get_data_at(i);
+ StringRef r = right->get_data_at(i);
+
+ if (!validate_utf8(l.data, l.size) || !validate_utf8(r.data,
r.size)) {
+ return Status::InvalidArgument("hamming_distance requires
valid UTF-8 strings");
+ }
+
+ size_t l_char_len = simd::VStringFunctions::get_char_len(l.data,
l.size);
+ size_t r_char_len = simd::VStringFunctions::get_char_len(r.data,
r.size);
+
+ if (l_char_len != r_char_len) {
+ return Status::InvalidArgument("hamming_distance requires
strings of equal length");
+ }
+
+ size_t l_pos = 0;
+ size_t r_pos = 0;
+ Int64 distance = 0;
+
+ while (l_pos < l.size && r_pos < r.size) {
+ uint8_t l_step =
simd::get_utf8_byte_length(static_cast<uint8_t>(l.data[l_pos]));
Review Comment:
for all non-utf8 inputs, we can put a fast path
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