PG_STAT_REPLICATION

startup: The thread is being started.
catchup: The thread is establishing a connection between the standby node and the primary node.
streaming: The thread has established a connection between the standby node and the primary node and is replicating data streams.
backup: The thread is sending a backup.
stopping: The thread is being stopped.

PG_STAT_REPLICATION displays information about the log synchronization thread, such as the locations where the sender sends logs and where the receiver receives logs. For details about the columns, see Table 1.

**Table 1** PG_STAT_REPLICATION columns
Name	Type	Description
pid	bigint	PID of the thread
usesysid	oid	User system ID.
usename	name	Username
application_name	text	Program name
client_addr	inet	Client address
client_hostname	text	Client name
client_port	integer	Port of the client
backend_start	timestamp with time zone	Start time of the program
state	text	Status of the log synchronization thread: startup: The thread is being started. catchup: The thread is establishing a connection between the standby node and the primary node. streaming: The thread has established a connection between the standby node and the primary node and is replicating data streams. backup: The thread is sending a backup. stopping: The thread is being stopped.
sender_sent_location	text	Location where the transmit sends logs
receiver_write_location	text	Location where the receive end writes logs
receiver_flush_location	text	Location where the receive end flushes logs
receiver_replay_location	text	Location where the receive end replays logs
sync_priority	integer	Priority of synchronous duplication (0 indicates asynchronization.)
sync_state	text	Synchronization state: async: asynchronous replication. sync: synchronous replication. potential: The standby node is asynchronous currently, but if a current synchronization node fails, the standby node becomes synchronous. quorum: switches between the synchronous and asynchronous states to ensure that there are more than a certain number of synchronous standby servers. Generally, the number of synchronous standby servers is (n+1)/2-1, where n indicates the total number of copies. Whether the standby server is synchronous depends on whether logs are received first. For details, see the description of the synchronous_standby_names parameter.