-- A replicated seat has several holders on record (novox/hq ADR 0223).
--
-- 0039 recorded one holder per seat, keyed by the seat: a handover replaced the row, so the seat was
-- never without a holder in between. The mesh's resolver is now held on more than one machine, each
-- answering the same names, and each of those holders is recorded — added by `seat <name> --add`,
-- never by being assigned. So a holding is keyed by the seat and the assignment holding it.
--
-- Nothing else changes. A handover (`seat <name> --to`) still leaves exactly one row, replacing every
-- holder in one transaction; whether a seat may have more than one is the seat's compiled definition,
-- judged by the controller before a row is added, and a store holding two for any other seat is
-- refused at resolution, naming the seat. Every existing row is one per seat, so it satisfies the new
-- key as it stands.
alter table seat_holding drop constraint seat_holding_pkey;
alter table seat_holding add primary key (seat, node, module);