Update change_settings.md

change_settings.md

@@ -30,4 +30,23 @@ select sourcefile, name,sourceline,error from pg_file_settings where error is no
 
 ```
 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;
+```