We use a macaddr8 that embeds a wall-clock timestamp (so they're ascending order, achieving data locality) with some additional shard and sequence-number bits.

We use a macaddr8 that embeds a wall-clock timestamp (so they're ascending order, achieving data locality) with some additional shard and sequence-number bits. It's worked really well for us: https://github.com/estuary/flow/blob/master/supabase/migrations/02_flowid.sql#L2-L70 https://github.com/estuary/flow/blob/master/supabase/migrati... we use macaddr8 instead of bigint, because it has a postgres serialization / JSON encoding which lossless-ly round-trips with browsers and it works well with PostgREST. The same CANNOT be said for bigint, which is a huge footgun.