domain(localhost) is empty

[khamin]

Describe the unexpected behaviour

SELECT domain('http://localhost') return empty string.

How to reproduce

• Which ClickHouse server version to use: 22.12.2

Expected behavior

Should return localhost.
Same for other single-level domains.

[cangyin]

That is expected. From comment of FunctionDomain, it returns:

ClickHouse/src/Functions/URL/domain.h

Lines 132 to 135 in c4f4a1d

	/// Extracts host from given url.
	///
	/// @return empty string view if the host is not valid (i.e. it does not have dot, or there no symbol after dot).
	inline std::string_view getURLHost(const char * data, size_t size)

[khamin]

That is expected. From comment of FunctionDomain, it returns:

ClickHouse/src/Functions/URL/domain.h

Lines 132 to 135 in c4f4a1d

	/// Extracts host from given url.
	///
	/// @return empty string view if the host is not valid (i.e. it does not have dot, or there no symbol after dot).
	inline std::string_view getURLHost(const char * data, size_t size)

It does not change the fact that localhost is a valid domain.

[den-crane]

duplicate #31106