add pg_database_size metric

Author: tmc

queries.yaml

@@ -98,3 +98,17 @@ pg_stat_user_tables:
     - autoanalyze_count:
         usage: "COUNTER"
         description: "Number of times this table has been analyzed by the autovacuum daemon"
+
+pg_database:
+  query: "SELECT d.datname AS name, pg_catalog.pg_get_userbyid(d.datdba) AS owner, CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT') THEN pg_catalog.pg_database_size(d.datname) ELSE 0 END AS size FROM pg_catalog.pg_database d ORDER BY CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT') THEN pg_catalog.pg_database_size(d.datname) ELSE NULL END DESC"
+  metrics:
+    - name:
+        usage: "LABEL"
+        description: "Name of the schema that this table is in"
+    - owner:
+        usage: "LABEL"
+        description: "Owner of this database"
+    - size:
+        usage: "GAUGE"
+        description: "Owner of this database"
+