postgresql-17-pg-failover-slots

About postgresql-17-pg-failover-slots

From Debian's package description

This extension is for anyone with Logical Replication Slots on Postgres databases that are also part of a Physical Streaming Replication architecture.

Since logical replication slots are only maintained on the primary node, downstream subscribers don't receive any new changes from a newly promoted primary until the slot is created, which is unsafe because the information that includes which data a subscriber has confirmed receiving and which log data still needs to be retained for the subscriber will have been lost, resulting in an unknown gap in data changes. PG Failover Slots makes logical replication slots usable across a physical failover using the following features:

• Copies any missing replication slots from the primary to the standby
• Removes any slots from the standby that aren't found on the primary
• Periodically synchronizes the position of slots on the standby based on the primary
• Ensures that selected standbys receive data before any of the logical slot walsenders can send data to consumers

From Debian's description of the postgresql-17-pg-failover-slots package, under that package's license.