feat: add a new plugin. The plugin show age in second and number of transactions that are currently prepared for two-phase commit. Plugin has graphs and prigger

Author: alexander popov

mamonsu/plugins/pgsql/__init__.py

@@ -5,5 +5,6 @@
 __all__ += ['cfs']
 __all__ += ['archive_command']
 __all__ += ['relations_size']
+__all__ += ['prepared_transaction']
 
 from . import *

mamonsu/plugins/pgsql/relations_size.py

@@ -82,11 +82,6 @@ def run(self, zbx):
 
         zbx.send('pgsql.relation.size[]', zbx.json({'data': rels}))
 
-
-    def items(self, template):
-
-        return ''
-
     def discovery_rules(self, template):
         rule = {
             'name': 'Relation size discovery',

mamonsu/tools/bootstrap/sql.py

@@ -117,6 +117,12 @@
 RETURNS TABLE(SETTING TEXT) AS $$
 select setting from pg_catalog.pg_settings where name = param
 $$ LANGUAGE SQL SECURITY DEFINER;
+
+CREATE OR REPLACE FUNCTION public.mamonsu_prepared_transaction()
+RETURNS TABLE(count_prepared BIGINT, oldest_prepared BIGINT) AS $$
+SELECT COUNT(*) AS count_prepared,
+coalesce (ROUND(MAX(EXTRACT (EPOCH FROM (now() - prepared)))),0)::bigint AS oldest_prepared  
+FROM pg_catalog.pg_prepared_xacts$$ LANGUAGE SQL SECURITY DEFINER;
 """
 
 GrantsOnSchemaSQL = """
@@ -145,4 +151,6 @@
 GRANT EXECUTE ON FUNCTION public.mamonsu_get_sys_param(param text) TO {1};
 
 GRANT EXECUTE ON FUNCTION public.mamonsu_get_connections_states() TO {1};
+
+GRANT EXECUTE ON FUNCTION public.mamonsu_prepared_transaction() TO {1};
 """

packaging/conf/example.conf

@@ -178,3 +178,11 @@ enabled = False
 relations=pg_catalog.pg_class,pg_catalog.pg_user
 interval = 500
 
+# Get age in second and number of transactions that are currently prepared for two-phase commit.
+# https://www.postgresql.org/docs/current/sql-prepare-transaction.html
+# https://www.postgresql.org/docs/12/view-pg-prepared-xacts.html
+# max_prepared_transaction_time - age of prepared pransaction in second,  after which the trigger run.
+# (возраст подготовленных транзакций, после которого срабатывает триггер.) ????
+[preparedtransaction]
+max_prepared_transaction_time = 60
+interval = 60