pg_promote (promotion)
Also called: promotion, promote signal, pg_ctl promote
pg_promote() is the PostgreSQL function that tells a standby to stop following the primary, exit recovery, and become a primary in its own right. Promotion ends replay, opens the database for writes, and advances the timeline so future WAL is distinguishable from the old primary's.
What this means
The function that tells a standby: stop following the primary, finish recovery, and become a primary yourself. Promotion ends replay, opens the database for writes, and bumps the timeline so the new primary's WAL can never be confused with the old one's.
Why it matters operationally
This is the actual verb behind every failover and switchover, whether you run it manually or a cluster manager like Patroni calls it for you. The timeline bump it triggers is what lets the rest of the cluster (and pg_rewind) tell the new history apart from the old.