---------------------  когда нужно снести

select * from pg_stat_activity where datname='......' \gx

select pg_terminate_backend(pid) from pg_stat_activity where datname='.......';

select pid,query  from pg_stat_activity where usename='v.koversunov' ;

select pg_terminate_backend(pid)  from pg_stat_activity where usename='v.koversunov' ;

• pg_cancel_backend(pid): Terminate a query but keep the connection alive
• pg_terminate_backend(pid): Terminate a query and kill the connection

select 'REASSIGN OWNED BY "'||usename||'" TO postgres;' from pg_user  order by usename;
select 'DROP OWNED BY "'||usename||'";' from pg_user  order by usename;
select 'DROP user "'||usename||'";' from pg_user order by usename;

postgres=# DROP user acc_data;
ERROR:  role "acc_data" cannot be dropped because some objects depend on it
DETAIL:  privileges for function pg_stat_statements_reset()

1. Before going to solution, list all privileges of a role (grantee)

Если таблиц стала занимать много места на диске, первым дело стоит проверить работу процесса autovacuum.
Проверить обрабатывал ли данную таблицу autovacuum:

SELECT schemaname, relname, n_live_tup, n_dead_tup, last_autovacuum
FROM
pg_stat_all_tables ORDER BY n_dead_tup/ (n_live_tup * current_setting('autovacuum_vacuum_scale_factor')::float8 + current_setting('autovacuum_vacuum_threshold')::float8);

postgres=# show archive_mode;
archive_mode 
--------------
off
(1 row)

postgres=# show archive_command;;
archive_command 
-----------------
(disabled)
(1 row) 
--Let’s create directories for backups and archives (login as root USER):

---------------------------------------   кто нуждается в вакууме
SELECT schemaname, relname, n_tup_ins as "inserts",n_tup_upd as "updates",n_tup_del as "deletes", n_live_tup as "live_tuples", n_dead_tup as "dead_tuples"
FROM pg_stat_user_tables 
--WHERE schemaname = 'scott' and relname = 'employee';
order by n_dead_tup desc;