perf(metrics): filter queries by current_database to reduce VM load

Author: Dementii Priadko

config/pgwatch-postgres/metrics.yml

@@ -8,7 +8,9 @@ metrics:
           queryid,
           query
         from pg_stat_statements
-        where queryid is not null
+        where
+          queryid is not null
+          and dbid = (select oid from pg_database where datname = current_database())
         order by total_exec_time desc
         limit 1000;
     gauges:

config/pgwatch-prometheus/metrics.yml

@@ -811,7 +811,9 @@ metrics:
             else relation::regclass::text 
           end as tag_table
         from pg_catalog.pg_locks blocked
-        where not blocked.granted
+        where
+          not blocked.granted
+          and database = (select oid from pg_database where datname = current_database())
         group by locktype, relation
         limit 5000
     gauges:
@@ -841,7 +843,11 @@ metrics:
           count(*) as transactions,
           coalesce(max(extract(epoch from (clock_timestamp() - xact_start)))::int8, 0) as age_in_seconds
         from pg_catalog.pg_stat_activity
-        where state is distinct from 'idle' and (now() - xact_start) > '1 minutes'::interval and query not like 'autovacuum:%'
+        where
+          state is distinct from 'idle'
+          and datname = current_database()
+          and (clock_timestamp() - xact_start) > '1 minutes'::interval
+          and query not like 'autovacuum:%'
     gauges:
       - '*'
     statement_timeout_seconds: 15
@@ -890,8 +896,8 @@ metrics:
             sum(current_setting('block_size')::int * pg_stat_statements.temp_blks_read) as temp_bytes_read,
             sum(current_setting('block_size')::int * pg_stat_statements.temp_blks_written) as temp_bytes_written
             from pg_stat_statements
-            join pg_database
-            on pg_database.oid = pg_stat_statements.dbid
+            join pg_database on pg_database.oid = pg_stat_statements.dbid
+            where pg_database.datname = current_database()
             group by pg_database.datname, pg_stat_statements.queryid
         )
         select
@@ -936,8 +942,8 @@ metrics:
             sum(current_setting('block_size')::int * pg_stat_statements.temp_blks_read) as temp_bytes_read,
             sum(current_setting('block_size')::int * pg_stat_statements.temp_blks_written) as temp_bytes_written
             from pg_stat_statements
-            join pg_database
-            on pg_database.oid = pg_stat_statements.dbid
+            join pg_database on pg_database.oid = pg_stat_statements.dbid
+            where pg_database.datname = current_database()
             group by pg_database.datname, pg_stat_statements.queryid
         )
         select
@@ -1129,7 +1135,10 @@ metrics:
       11: |
         select current_database() as tag_datname, count(*) as queries /* pgwatch_generated */
         from pg_catalog.pg_stat_activity
-        where state = 'idle in transaction' and (now() - query_start) > '10 minutes'::interval
+        where
+          state = 'idle in transaction'
+          and datname = current_database()
+          and (clock_timestamp() - state_change) > '1 minutes'::interval
     gauges:
       - queries
     statement_timeout_seconds: 15
@@ -2027,14 +2036,15 @@ metrics:
           S.heap_blks_scanned::float,
           S.heap_blks_vacuumed::float,
           S.index_vacuum_count::float,
-          (S.max_dead_tuples / 1024 / 1024)::float as max_dead_tuples_mb,
+          (S.max_dead_tuples::float / 1024 / 1024) as max_dead_tuples_mb,
           S.num_dead_tuples::float as num_dead_item_ids
         from
           pg_stat_progress_vacuum as S
           join pg_database D on (S.datid = D.oid)
           join pg_stat_activity as A on (S.pid = A.pid)
           join pg_class C on (C.oid = S.relid)
           join pg_namespace N on (N.oid = C.relnamespace)
+        where D.datname = current_database()
       17: |
         select /* pgwatch_generated */
           current_database() as tag_datname,
@@ -2079,6 +2089,7 @@ metrics:
           join pg_stat_activity as A on (S.pid = A.pid)
           join pg_class C on (C.oid = S.relid)
           join pg_namespace N on (N.oid = C.relnamespace)
+        where D.datname = current_database()
     gauges:
       - '*'
     statement_timeout_seconds: 15