Added a pg_class metric

Author: dementii-priadko

config/pgwatch-prometheus/metrics.yml

@@ -966,34 +966,33 @@ metrics:
       - wal_bytes
       - temp_bytes_read
       - temp_bytes_written
-  pg_index_tuples:
+  pg_class:
     description: >
-      Track tuple counts (live, dead, and total) for indexes using reltuples from pg_class.
-      This metric provides insights into index tuple distribution and can help identify
-      indexes that may benefit from maintenance operations.
+      Direct access to pg_class system catalog data for all relations (tables, indexes, etc).
+      Provides reltuples, relpages, and other pg_class columns with relname and schemaname
+      as tags for easy filtering and querying.
     sqls:
       11: |
         select 
           current_database() as tag_datname,
           n.nspname as tag_schemaname,
-          t.relname as tag_tablename,
-          i.relname as tag_indexname,
-          i.reltuples as total_tuples,
-          coalesce(pg_stat_get_live_tuples(t.oid), 0) as live_tuples,
-          coalesce(pg_stat_get_dead_tuples(t.oid), 0) as dead_tuples
-        from pg_class i
-        join pg_index idx on idx.indexrelid = i.oid
-        join pg_class t on t.oid = idx.indrelid
-        join pg_namespace n on n.oid = i.relnamespace
-        where i.relkind = 'i'
-          and t.relkind = 'r'
-          and n.nspname not in ('information_schema', 'pg_catalog')
-        order by i.reltuples desc nulls last
-        limit 5000
+          c.relname as tag_relname,
+          c.relkind as tag_relkind,
+          c.reltuples,
+          c.relpages,
+          pg_relation_size(c.oid) as relation_size_bytes,
+          pg_total_relation_size(c.oid) as total_relation_size_bytes
+        from pg_class c
+        join pg_namespace n on n.oid = c.relnamespace
+        where n.nspname not in ('information_schema', 'pg_catalog')
+          and c.relkind in ('r', 'i', 'm', 'v')  -- tables, indexes, materialized views, views
+        order by pg_total_relation_size(c.oid) desc
+        limit 10000
     gauges:
-      - total_tuples
-      - live_tuples
-      - dead_tuples
+      - reltuples
+      - relpages
+      - relation_size_bytes
+      - total_relation_size_bytes
   pg_stat_user_indexes:
     sqls:
       11: |
@@ -1985,7 +1984,7 @@ presets:
       pg_stat_wal_receiver: 30
       pg_archiver: 30
       pg_stat_user_tables: 30
-      pg_index_tuples: 30
+      pg_class: 30
       pg_stat_user_indexes: 30
       pg_stat_statements: 30
       pg_stat_replication: 30