# 31.8. Configuration Settings

Logical replication requires several configuration options to be set.

On the publisher side,wal_levelmust be set tological, andmax_replication_slotsmust be set to at least the number of subscriptions expected to connect, plus some reserve for table synchronization. Andmax_wal_sendersshould be set to at least the same asmax_replication_slotsplus the number of physical replicas that are connected at the same time.

max_replication_slotsmust also be set on the subscriber. It should be set to at least the number of subscriptions that will be added to the subscriber, plus some reserve for table synchronization.max_logical_replication_workersmust be set to at least the number of subscriptions, again plus some reserve for the table synchronization. Additionally themax_worker_processesmay need to be adjusted to accommodate for replication workers, at least (max_logical_replication_workers+1). Note that some extensions and parallel queries also take worker slots frommax_worker_processes.