Before performing the setup of the database multiplexing mode, ensure that the prerequisite streaming replication feature has been set up correctly.

Perform the following procedure:

1. On the primary server, ensure that single-row searches can be performed using the pg_stat_replication statistics view.

   An example output of the psql command is shown below.

   Example)

   postgres=# select * from pg_stat_replication;
   -[ RECORD 1 ]----+------------------------------
   pid              | 10651
   usesysid         | 10
   usename          | fsep
   application_name | standby
   client_addr      | 192.0.2.210
   client_hostname  |
   client_port      | 55098
   backend_start    | 2022-03-23 11:17:49.628793+09
   backend_xmin     |
   state            | streaming
   sent_lsn         | 0/3000060
   write_lsn        | 0/3000060
   flush_lsn        | 0/3000060
   replay_lsn       | 0/3000060
   write_lag        |
   flush_lag        |
   replay_lag       |
   sync_priority    | 1
   sync_state       | sync
   reply_time       | 2022-03-23 11:23:27.703366+09

2. Confirm the search results of step 1.

   Ensure that the connection established with the intended standby server is in synchronous mode.

   Table 2.7 Items to be checked

   Item	Required value
   application_name	Value specified for synchronous_standby_names parameter in the postgresql.conf file of the primary server.
   client_addr	IP address of the standby server.
   state	"streaming".
   sync_state	"sync".