Список текущих подключению можно посмотреть с помощью запроса:

SELECT * FROM pg_catalog.pg_stat_activity;

Например,

postgres=# SELECT * FROM pg_catalog.pg_stat_activity;
 datid | datname  | procpid | usesysid | usename  |               current_query                | waiting |          xact_start           |          query_start          |         backend_start         | client_addr | client_port
-------+----------+---------+----------+----------+--------------------------------------------+---------+-------------------------------+-------------------------------+-------------------------------+-------------+-------------
 11564 | postgres |   20292 |       10 | postgres | SELECT * FROM pg_catalog.pg_stat_activity; | f       | 2009-12-28 15:19:01.134017+03 | 2009-12-28 15:19:01.134017+03 | 2009-12-28 15:10:47.749687+03 |             |          -1
(1 ROW)