On Mon, 2025-09-08 at 15:03 +0000, legrand legrand wrote: > For some projects we need a fast manual switchover to address Near Zero downtime maintenance > (not speaking here about automated failover like those provided by HA tools, but just planned, controlled operations) > > Database Physical replication switchover itself: > - initial replication (before switchover) should be synchronous or replication LAG should be controlled to prevent data loss. > - Switchover duration seems not "compressible" under a few seconds (because of primary shutdown, promotion, new standby catch up, ...) > - Application retry strategy (after disconnection) should be tuned using proper retry delay. Pooler or specific driver may help. There is no need for synchronous replication; you cannot lose data with a switchover, if you do it right: - run a CHACKPOINT on the primary (to speed up the shutdown) - when the checkpoint is done, perform a clean shutdown - when the primary is down, promote the standby The primary will transmit *all* data to the standby before it shuts down. > May logical replication ( bi-directional, with one instance RW and the other RO) be a better solution ? I'd say no. > what could we expect (in term of downtime in both worlds) ? Usually seconds, so plan for ten minutes. Yours, Laurenz Albe
