pg_replication_slots   The pg_replication_slots view provides a listing
   of all replication slots that currently exist on the database cluster,
   along with their current state.
  
For more on replication slots, see Section 26.2.6 and Chapter 48.
Table 51.81. pg_replication_slots Columns
| Name | Type | References | Description | 
|---|---|---|---|
| slot_name | name | A unique, cluster-wide identifier for the replication slot | |
| plugin | name | The base name of the shared object containing the output plugin this logical slot is using, or null for physical slots. | |
| slot_type | text | The slot type - physicalorlogical | |
| datoid | oid |  | The OID of the database this slot is associated with, or null. Only logical slots have an associated database. | 
| database | text |  | The name of the database this slot is associated with, or null. Only logical slots have an associated database. | 
| temporary | boolean | True if this is a temporary replication slot. Temporary slots are not saved to disk and are automatically dropped on error or when the session has finished. | |
| active | boolean | True if this slot is currently actively being used | |
| active_pid | integer | The process ID of the session using this slot if the slot
       is currently actively being used. NULLif
       inactive. | |
| xmin | xid | The oldest transaction that this slot needs the database to
      retain. VACUUMcannot remove tuples deleted
      by any later transaction. | |
| catalog_xmin | xid | The oldest transaction affecting the system catalogs that this
      slot needs the database to retain. VACUUMcannot
      remove catalog tuples deleted by any later transaction. | |
| restart_lsn | pg_lsn | The address ( LSN) of oldest WAL which still
      might be required by the consumer of this slot and thus won't be
      automatically removed during checkpoints. | |
| confirmed_flush_lsn | pg_lsn | The address ( LSN) up to which the logical
      slot's consumer has confirmed receiving data. Data older than this is
      not available anymore.NULLfor physical slots. |