Added new sql script for checking PostgreSQL configuration over pg_settings view.

sql/check_config.sql

@@ -0,0 +1,68 @@
+/* This query is used for getting non default configuration parameters in PostgreSQL.
+   For user/client sessions you can see modified parameters, but reset_val will contain value from configuration file (I hope).
+   If you see (*) before config name it means that parameter has default value.
+   If you see (c) after config name it means that parameter was changed for client session or by another reason (database, user, etc).
+   If you see !!! after config name it means that parameter were changed in file but still not apllied.
+   All fields in report are aligned by width for simplifying a compare procedures.
+*/
+with icp (name) as (
+  values ('listen_addresses'), ('max_connections'), ('superuser_reserved_connections'), ('shared_buffers')
+       , ('work_mem'), ('maintenance_work_mem'), ('shared_preload_libraries'), ('vacuum_cost_delay')
+       , ('vacuum_cost_page_hit'), ('vacuum_cost_page_miss'), ('vacuum_cost_page_dirty'), ('vacuum_cost_limit')
+       , ('bgwriter_delay'), ('bgwriter_lru_maxpages'), ('bgwriter_lru_multiplier'), ('effective_io_concurrency')
+       , ('max_worker_processes'), ('wal_level'), ('synchronous_commit'), ('checkpoint_timeout')
+       , ('min_wal_size'), ('max_wal_size'), ('checkpoint_completion_target'), ('max_wal_senders')
+       , ('hot_standby'), ('max_standby_streaming_delay'), ('hot_standby_feedback'), ('effective_cache_size')
+       , ('log_directory'), ('log_filename'), ('log_min_duration_statement'), ('log_checkpoints')
+       , ('log_line_prefix'), ('log_lock_waits'), ('log_replication_commands'), ('log_temp_files')
+       , ('track_io_timing'), ('track_functions'), ('track_activity_query_size'), ('log_autovacuum_min_duration')
+       , ('autovacuum_max_workers'), ('autovacuum_naptime'), ('autovacuum_vacuum_threshold')
+       , ('autovacuum_analyze_threshold'), ('autovacuum_vacuum_scale_factor'), ('autovacuum_analyze_scale_factor')
+       , ('autovacuum_vacuum_cost_delay'), ('vacuum_freeze_min_age'), ('vacuum_freeze_table_age')
+       , ('pg_stat_statements.max'), ('pg_stat_statements.track')
+       , ('pg_stat_statements.track_utility'), ('pg_stat_statements.save')
+)
+select rpad (case when source in ('default', 'override') then '(*) ' else '    ' end || 
+             rpad (name, 35) ||
+             case when setting != reset_val then ' (c)' else '' end ||
+             case when pending_restart then ' !!!' else '' end
+            , 47) as name
+     , rpad (case when (unit = '8kB' and setting != '-1') then pg_size_pretty (setting::bigint * 8192) 
+                  when (unit = 'kB' and  setting != '-1') then pg_size_pretty (setting::bigint * 1024) 
+                  else setting end, 25) as setting
+     , rpad (case when unit in ('8kB', 'kB') then 'byte' else unit end, 4) as unit
+     , rpad (case when (unit = '8kB' and reset_val != '-1') then pg_size_pretty (reset_val::bigint * 8192) 
+                  when (unit = 'kB' and  reset_val != '-1') then pg_size_pretty (reset_val::bigint * 1024) 
+                  else reset_val end, 25) as reset_val
+     , rpad (case when (unit = '8kB' and boot_val != '-1') then pg_size_pretty (boot_val::bigint * 8192) 
+                  when (unit = 'kB' and  boot_val != '-1') then pg_size_pretty (boot_val::bigint * 1024) 
+                  else boot_val end, 25) as boot_val
+     , rpad (case source
+               when 'environment variable' then 'env'
+               when 'configuration file' then '.conf'
+               when 'configuration file' then '.conf'
+               else source
+             end
+            , 13) as source
+     --, sourcefile
+  from pg_settings
+ where (sourcefile is not null
+    or pending_restart
+    or setting != boot_val
+    or reset_val != boot_val
+    or exists (select 1 from icp where icp.name = pg_settings.name)
+    or source not in ('default', 'override'))
+   and (name, setting) not in ( ('log_filename', 'postgresql-%Y-%m-%d.log')
+                              , ('log_checkpoints', 'on')
+                              , ('logging_collector', 'on')
+                              , ('log_line_prefix', '%m %p %u@%d from %h [vxid:%v txid:%x] [%i] ')
+                              , ('log_replication_commands', 'on')
+                              , ('log_destination', 'stderr')
+                              , ('log_file_mode', '0600')
+                              , ('unix_socket_permissions', '0777')
+                              , ('transaction_read_only', 'on')
+                              , ('transaction_read_only', 'off')
+                              , ('application_name', 'psql')
+                              , ('archive_command', '(disabled)')
+                              )
+ order by category, name;