Sequencer

Hand out identifiers that are unique across every node without a central bottleneck — and decide whether those IDs must also be sortable or monotonic. Getting this wrong shows up late and hard: collisions corrupt data, a single allocator caps write throughput, and IDs that leak a creation time or a sequential count expose business secrets and enable enumeration attacks.

When to reach for this

A system writes new records across multiple nodes and each needs a primary key (orders, messages, uploads, events). Reach for this when a single auto-increment column would serialize all writes, when IDs must be generated before a DB round trip (client-side, offline), or when records must be roughly time-ordered without a separate sort field.