Getting error `replication slot "pgl_testdb_pgnode_pdaaa79d_sub1" does not exist`

Question

I have a 3 node cluster having logical replication enabled and subscriber connected to the virtual IP pointing to the current leader/master under the cluster setup. Data is getting streaming/replicated to the subscriber.

Whenever the master node goes down and one of the replicas promotes itself as master in that case logical replication stops stating below error

2021-04-13T09:32:12.912262+00:00 host2 postgres_2[13527]: [7-1] pid=13527,session=6075651c.34d7,line=1,sqlstate=42704,user_app=sub1,user=bpuser,db=testdb,client=10.186.34.182,txId=0 ERROR: replication slot "pgl_testdb_pgnode_pdaaa79d_sub1" does not exist

This error occurs on the new Master, I am using postgres 12

Answer 1

Replication slots exist only on the primary server, so they are lost when the primary server goes down (and doesn't come up again).

The only safe way I can think of to recover is to build the logical replication standbys from scratch after a failover. I don't think that logical replication can be used for a good high-availability solution.