Configuration Settings

Publication-subscription requires some configuration options to be set.

On the publisher side, wal_level must be set to logical, and the value of max_replication_slots must be at least the number of subscriptions expected to be connected plus the number of connections reserved for table synchronization. Value of max_wal_senders ≥ Value of max_replication_slots + Number of physical replication slots that are connected at the same time + 1

NOTE: If a subscriber is activated and subscribes to a publication, a temporary connection to the publisher needs to be established to check whether the publication subscribed to by the subscriber exists on the publisher. The publisher creates a temporary WAL sender. After the temporary connection is used up, it is disconnected and released immediately.

max_replication_slots must also be set on the subscriber. It must be set to at least the number of subscriptions that will be added to the subscriber. max_logical_replication_workers must be set to at least the number of subscriptions plus the number of connections reserved for table synchronization.