# Managing logical slot synchronization for RDS for PostgreSQL
<a name="Appendix.PostgreSQL.CommonDBATasks.pglogical.slot.synchronization"></a>

Starting in community PostgreSQL 17, a new feature to automatically synchronize logical replication slots from primary to standby servers has been introduced through the parameter `sync_replication_slots` or the related function `pg_sync_replication_slots()`, which manually synchronizes slots on execution.

These features are available starting with RDS for PostgreSQL 17. A typical setup will have a primary instance and its [read replica](USER_PostgreSQL.Replication.ReadReplicas.md), as well as a logical replication subscriber to the primary.

Ensure the subscription is created with the failover option set to true:

```
CREATE SUBSCRIPTION subname CONNECTION 'host=...' PUBLICATION pubname WITH (failover = true);
```

This creates a logical slot on the publisher with failover enabled.

```
postgres=> SELECT slot_name, slot_type, failover FROM pg_catalog.pg_replication_slots;
 slot_name | slot_type | failover 
-----------+-----------+----------
 subname   | logical   | t
(1 row)
```

By enabling slot synchronization, all of the failover logical replication slots on the primary are automatically created on the physical standbys and are synced periodically. Ensure the following values have been set through [parameter groups](USER_WorkingWithParamGroups.Associating.md):
+ `rds.logical_replication` must be `1` to enable logical replication
+ `hot_standby_feedback` must be `1` on the standby
+ `rds.logical_slot_sync_dbname` on the standby must be set to a valid database name

  The parameter's default value is `postgres`. If the logical publishing instance has the `postgres` database, the default parameter does not need to be changed.
+ `synchronized_standby_slots` on the primary must be set to the physical replication slot of the standby intended to be in-sync
+ `sync_replication_slots` must be `1` to enable automatic synchronization

With a failover-enabled subscription slot and the above parameter values, when a standby is promoted, the subscriber can alter its subscription to this newly promoted instance and continue logical replication seamlessly.