0247 — No deliveries.status index until real evidence demands one

Context. Keeping deliveries as one shared table (0246) raises a throughput concern at scale, and a status index was considered for the reads that concern implies.

Decision. The index was deliberately not added preemptively. status is touched on nearly every write, so today’s writes likely already get Postgres’s HOT-update fast path — an index on status would end that fast path for every topic’s every state transition, to speed up a read that is only expensive in an already-contained case. Filed to revisit with real evidence instead of speculatively.

Consequences. Write-path performance is protected by default; the read stays unindexed until measurement shows it matters. Anyone tempted to add the index later must weigh it against losing HOT updates on the hottest write path in the table.