Remove unsigned integer types from core types

[dimitri-yatsenko]

Summary

Remove unsigned integer types (uint8, uint16, uint32, uint64) from DataJoint's core type system for v2.0. These types are MySQL-specific and not portable to PostgreSQL and other database backends.

Motivation

DataJoint 2.0 is in pre-release and aims to support multiple database backends (PostgreSQL support coming in v2.1). Unsigned integer types only exist in MySQL, creating portability issues:

• PostgreSQL: Must promote to larger signed types (e.g., uint16 would map to INTEGER)
• Storage overhead: 2-4 extra bytes per value when promoted
• Confusion: Unclear what types are truly portable

Since v2.0 already requires migration from 0.14.6, this is the ideal time to establish a clean, portable core type system.

Changes

Implementation (src/datajoint/declare.py)

• REMOVED uint8, uint16, uint32, uint64 from CORE_TYPES dictionary
• These types no longer exist as core DataJoint types
• They are not passed through or supported

Tests (6 files updated)

Replaced all unsigned core types with signed equivalents:

• uint8 → int16 (larger signed type for unsigned 8-bit range)
• uint16 → int32 (larger signed type for unsigned 16-bit range)
• uint32 → int64 (larger signed type for unsigned 32-bit range)

Files:

• tests/schema_simple.py - E.M.id_m
• tests/schema_type_aliases.py - Removed unsigned types from test table
• tests/schema.py - Auto.id, Ephys.Channel.channel
• tests/schema_university.py - Student.student_id, Course.course
• tests/integration/test_type_aliases.py - Removed unsigned type test cases
• tests/integration/test_hidden_job_metadata.py - All uint8 → int16

Note: test_blob.py and test_blob_matlab.py unchanged (testing numpy dtypes in serialization, not DataJoint table definitions).

Migration Path

OLD (0.14.6, no longer works in 2.0):

mouse_id : uint32   # ❌ Core type removed

NEW (2.0, portable):

mouse_id : int64    # ✅ Use larger signed core type

Alternative (MySQL-only, not portable):

mouse_id : int unsigned   # ⚠️ Native MySQL type (with warning)

Core Types After This Change

Signed integers only:

• int8 → TINYINT
• int16 → SMALLINT
• int32 → INT
• int64 → BIGINT

Unsigned removed:

• uint8 ❌ REMOVED
• uint16 ❌ REMOVED
• uint32 ❌ REMOVED
• uint64 ❌ REMOVED

Users who need unsigned integers must use native MySQL types like tinyint unsigned, int unsigned, etc., which will trigger warnings about non-portable types.

Impact

Who is affected:

• Users migrating from 0.14.6 with schemas using uint8, uint16, uint32, uint64 core types
• These types will cause errors (unknown type)

Migration:

• Simple find-replace in schema definitions
• No data migration needed (values remain compatible)
• Example: mouse_id : uint32 → mouse_id : int64

Why this is acceptable:

• ✅ v2.0 is pre-release - perfect time for breaking changes
• ✅ Already requires migration from 0.14.6
• ✅ Creates clean foundation for multi-database support (v2.1)
• ✅ Easy migration path (find-replace in code)
• ✅ No data migration required

Related

• Part of v2.0 core type system revision
• Establishes foundation for v2.1 PostgreSQL support (branch pre/v2.1)
• See: PROPOSAL_CORE_TYPES_REVISION.md for full rationale

Testing

• All existing tests updated to use signed types
• Tests pass with new core type system
• CI will validate on both Python versions and MySQL versions