The following bug has been logged on the website:
Bug reference: 14036
Logged by: Jamie Koceniak
Email address: jkoceniak(at)mediamath(dot)com
PostgreSQL version: 9.4.6
Operating system: Debian
Description:
We just configured 6 replication slots and I noticed that 2 of the 6
replication slots have a NULL value for xmin. Is this problematic?
postgres=# select slot_name, xmin from pg_replication_slots;
slot_name | xmin
----------------+------------
standb5 | 1571582845
standby3 | 1571582849
standby6 | 1571582850
standby4 | 1571582853
standby2 |
standby1 |