ID-Encoded Placement

Embed an object's storage location directly in its identifier — shard bits, type bits, local row bits packed into one integer — so that finding any object is arithmetic every client can perform, with no lookup service, directory tier, or hash ring on the read path. Identifier generation collapses into the same stroke: insert into the chosen shard, take the auto-incremented local ID, and the composed integer is a universally unique ID whose top bits are its address.

The scheme's power and its constraint are the same fact: because every stored reference contains the address, the address can never change — data is pinned to its shard for life, and rebalancing happens by moving whole shards between machines, never objects between shards. Boundary against hash-based placement (consistent hashing, mod-sharding): there the key is hashed to find a location, so placement can be recomputed when topology changes, at the cost of a hash function standing between every lookup and its data; ID-encoded placement removes the function and freezes the answer.