Fix index bloat metrics for user schemas by replacing pg_stats with public.pg_statistic view

Author: dementii-priadko

README.md

@@ -20,13 +20,20 @@ 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;
 
--- Create a public view for pg_statistic access for bloat metrics
+-- Create a public view for pg_statistic access (required for bloat metrics on user schemas)
 CREATE VIEW public.pg_statistic AS
- SELECT pg_statistic.stawidth,
-    pg_statistic.stanullfrac,
-    pg_statistic.starelid,
-    pg_statistic.staattnum
-   FROM pg_statistic;
+SELECT 
+    n.nspname as schemaname,
+    c.relname as tablename,
+    a.attname,
+    s.stanullfrac as null_frac,
+    s.stawidth as avg_width,
+    false as inherited
+FROM pg_statistic s
+JOIN pg_class c ON c.oid = s.starelid
+JOIN pg_namespace n ON n.oid = c.relnamespace  
+JOIN pg_attribute a ON a.attrelid = s.starelid AND a.attnum = s.staattnum
+WHERE a.attnum > 0 AND NOT a.attisdropped;
 
 GRANT SELECT ON public.pg_statistic TO pg_monitor;
 ALTER USER postgres_ai_mon set search_path = "$user", public, pg_catalog;

config/pgwatch-prometheus/metrics.yml

@@ -1512,9 +1512,9 @@ metrics:
                           and a2.attnum = ic.attpos
                     ) i
                     join pg_catalog.pg_namespace n on n.oid = i.relnamespace
-                    join pg_catalog.pg_stats s on s.schemaname = n.nspname
-                                              and s.tablename = i.attrelname
-                                              and s.attname = i.attname
+                                join public.pg_statistic s on s.schemaname = n.nspname
+                                      and s.tablename = i.attrelname
+                                      and s.attname = i.attname
                     group by 1,2,3,4,5,6,7,8,9,10,11
               ) as rows_data_stats
           ) as rows_hdr_pdg_stats
@@ -1583,7 +1583,7 @@ metrics:
               from pg_attribute as att
                 join pg_class as tbl on att.attrelid = tbl.oid
                 join pg_namespace as ns on ns.oid = tbl.relnamespace
-                left join pg_stats as s on s.schemaname=ns.nspname
+                left join public.pg_statistic as s on s.schemaname=ns.nspname
                   and s.tablename = tbl.relname and s.inherited=false and s.attname=att.attname
                 left join pg_class as toast on tbl.reltoastrelid = toast.oid
               where not att.attisdropped

config/target-db/init.sql

@@ -21,12 +21,19 @@ GRANT CONNECT ON DATABASE target_database TO monitor;
 GRANT USAGE ON SCHEMA public TO monitor;
 
 -- Create a public view for pg_statistic access
-CREATE VIEW public.pg_statistic AS
- SELECT pg_statistic.stawidth,
-    pg_statistic.stanullfrac,
-    pg_statistic.starelid,
-    pg_statistic.staattnum
-   FROM pg_statistic;
+CREATE OR REPLACE VIEW public.pg_statistic AS
+SELECT 
+    n.nspname as schemaname,
+    c.relname as tablename,
+    a.attname,
+    s.stanullfrac as null_frac,
+    s.stawidth as avg_width,
+    false as inherited
+FROM pg_statistic s
+JOIN pg_class c ON c.oid = s.starelid
+JOIN pg_namespace n ON n.oid = c.relnamespace  
+JOIN pg_attribute a ON a.attrelid = s.starelid AND a.attnum = s.staattnum
+WHERE a.attnum > 0 AND NOT a.attisdropped;
 
 -- Grant specific access instead of all tables
 GRANT SELECT ON public.pg_statistic TO pg_monitor;