But the system can die/crash before shutdown.
You mean it will not write WAL?
When a logical replication slot is created we build a snapshot and also
write to WAL:
postgres=# select pg_current_wal_insert_lsn(); select
pg_create_logical_replication_slot('foo', 'pgoutput'); select
pg_current_wal_insert_lsn();
pg_current_wal_insert_lsn
---------------------------
0/37F96F8
(1 row)
pg_create_logical_replication_slot
------------------------------------
(foo,0/37F9730)
(1 row)
pg_current_wal_insert_lsn
---------------------------
0/37F9730
(1 row)
Only after that slot is marked as persistent.
Regards,
--
Alexander Kukushkin
