Column Ordering Standards & UUIDv7 Keys

To maximize developer ergonomics in C# while enforcing deterministic, professional database schemas:

• In C# Domain Entities: All properties MUST be declared in Alphabetical Order (A-Z).
• In Physical PostgreSQL Tables: Metadata columns are enforced at positions 0 to 10 via EF Core .HasColumnOrder(), while business columns begin sequentially at position 11+ in logical domain order:

Column Position	Column Name	Type	Description
0	id	uuid	Primary Key (Guid v7)
1	tenant_id	uuid	Tenant isolation key (if entity implements IMustHaveTenant)
2	branch_id	uuid	Branch isolation key (if entity implements IMustHaveBranch)
3	created_at	timestamptz	Audit creation timestamp
4	created_by	uuid	User ID who created the record
5	last_modified_at	timestamptz	Audit last update timestamp
6	last_modified_by	uuid	User ID who last updated the record
7	is_deleted	boolean	Soft-delete flag
8	deleted_at	timestamptz	Audit soft-deletion timestamp
9	deleted_by	uuid	User ID who soft-deleted the record
10	version	integer	Optimistic concurrency control version
11+	Business columns	varies	Specific business domain attributes in logical order

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2. Guid v7 (UUIDv7) as Standard Primary Key

100% of domain entities and aggregates use Guid.CreateVersion7() as their primary key.

Why UUIDv7?

• Temporal Sorting: The first 48 bits encode a Unix timestamp with millisecond precision, ensuring records naturally sort in chronological order.
• B-Tree Index Performance: Eliminates the random insertion fragmentation caused by UUIDv4, maintaining high-throughput B-Tree indexing inside PostgreSQL.