Removed unnecessary grants from readme, changed naming in multixact_size metric to be more specific

Author: dementii-priadko

README.md

@@ -95,10 +95,6 @@ create user postgres_ai_mon with password '<password>';
 grant connect on database <database_name> to postgres_ai_mon;
 
 grant pg_monitor to postgres_ai_mon;
-grant select on pg_stat_statements to postgres_ai_mon;
-grant select on pg_stat_database to postgres_ai_mon;
-grant select on pg_stat_user_tables to postgres_ai_mon;
-grant select on pg_stat_user_indexes to postgres_ai_mon;
 grant select on pg_index to postgres_ai_mon;
 
 -- Create a public view for pg_statistic access (optional, for bloat analysis)

config/pgwatch-prometheus/metrics.yml

@@ -2214,11 +2214,11 @@ metrics:
             ) as has_rds_fn,
             coalesce(pg_has_role('pg_read_server_files','usage'), false) as has_read_files,
             (select rolsuper from pg_roles where rolname = current_user) as is_super,
-            exists (select from pg_proc where proname = 'pg_ls_dir')    as has_ls,
-            exists (select 1 from pg_proc where proname = 'pg_stat_file') as has_stat
+            exists (select from pg_proc where proname = 'pg_ls_dir')    as has_pg_ls_dir_func,
+            exists (select from pg_proc where proname = 'pg_stat_file') as has_pg_stat_file_func
         ),
         can_local as (
-          select (has_ls and has_stat and (has_read_files or is_super)) as ok from env
+          select (has_pg_ls_dir_func and has_pg_stat_file_func and (has_read_files or is_super)) as ok from env
         ),
         -- Use query_to_xml to safely execute RDS-specific multixact directory listing query.
         -- The XML wrapper allows the query to fail gracefully if rds_tools.pg_ls_multixactdir()