Fixed uuid first bit flipping issue.

[khustup2]

🚀 🚀 Pull Request

Impact

• Bug fix (non-breaking change which fixes expected existing functionality)
• Enhancement/New feature (adds functionality without impacting existing logic)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Things to be aware of

Things to worry about

Additional Context

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

This PR fixes a critical UUID data corruption bug where UUIDs with leading '00' bytes were being incorrectly converted to '80' during string conversion. The root cause was DuckDB's internal storage format flipping the top bit of UUIDs for ordering consistency, which wasn't being reversed during conversion to PostgreSQL format.

Key changes:

• Added bit-flip reversal logic in UUID-to-string conversion to correctly restore original UUID values
• Added comprehensive test coverage for UUID edge cases (0x00, 0x0F, 0x10, 0x80, 0xFF byte prefixes)
• Updated format specifiers from %x to %lx for correct handling of 64-bit values

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
cpp/deeplake_pg/duckdb_pg_convert.cpp	Implements bit-flip reversal and corrects format specifiers in UUID conversion logic
postgres/tests/py_tests/test_uuid_corruption.py	Adds comprehensive test suite validating UUID integrity across edge cases and NULL handling

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[Copilot]

The format specifiers use %lx which expects unsigned long, but the size of unsigned long is platform-dependent (32-bit on Windows, 64-bit on most Unix systems). Since we're working with explicit 64-bit values from uint64_t, consider using %016llx format specifier with unsigned long long casts, or use PRIx64 from <inttypes.h> for guaranteed portability across platforms.

Suggested change

	"%08lx-%04lx-%04lx-%04lx-%012lx",
	(unsigned long)((upper_flipped >> 32) & 0xFFFFFFFFUL),
	(unsigned long)((upper_flipped >> 16) & 0xFFFFUL),
	(unsigned long)(upper_flipped & 0xFFFFUL),
	(unsigned long)((uuid_val.lower >> 48) & 0xFFFFUL),
	(unsigned long)(uuid_val.lower & 0xFFFFFFFFFFFFUL));
	"%08llx-%04llx-%04llx-%04llx-%012llx",
	(unsigned long long)((upper_flipped >> 32) & 0xFFFFFFFFULL),
	(unsigned long long)((upper_flipped >> 16) & 0xFFFFULL),
	(unsigned long long)(upper_flipped & 0xFFFFULL),
	(unsigned long long)((uuid_val.lower >> 48) & 0xFFFFULL),
	(unsigned long long)(uuid_val.lower & 0xFFFFFFFFFFFFULL));