Mastering PostgreSQL 9.6

Handling physical replication slots

To make use of replication slots, changes have to be made to the postgresql.conf file:

wal_level = logical max_replication_slots = 5      # or whatever number is needed 

With physical slots, logical is not yet necessary—replica is enough. However, for logical slots, we need a higher wal_level setting. Then the max_replication_slots setting has to be changed. Basically, just put in a number that serves your purpose. My recommendation is to add some spare slots so that you can easily attach more consumers without restarting the server along the way.

After a restart, the slot can already be created:

test=# x Expanded display is on. test=# df *create*physical*slot* List of functions -[ RECORD 1 ]-------+---------------------------------------------------------------------- ...