postgresql_hacks/change_settings.md

How to reload config changes during the runtime (SIGHUP)?

select pg_reload_conf();

Does changing a config setting require a restart of postgresql or just a reload (SIGHUP)?

This can be archived by simply selecting the setting from pg_settings.

select context from pg_settings where name='max_wal_size';

Is a restart of postgresql required?

select pending_restart from pg_settings where name='max_wal_size';

This will tell you if a restart is pending for a setting.

How to check configuration (postgresql.conf) for configuration errors

select sourcefile, name,sourceline,error from pg_file_settings where error is not null;

How to check pg_hba.conf for configuration errors

select pg_hba_file_rules();

Check vacuuming and autovacuuming date for tables per database

Switch to the desired database and then you run this query to see the vaccum status.

SELECT 
    schemaname, 
    relname, 
    last_vacuum, 
    last_autovacuum, 
    n_dead_tup 
FROM 
    pg_stat_all_tables
WHERE 
    schemaname NOT IN ('pg_catalog', 'information_schema')
ORDER BY 
    n_dead_tup DESC;