diff --git a/patroni/api.py b/patroni/api.py
index a7a754a3..4647e7c2 100644
--- a/patroni/api.py
+++ b/patroni/api.py
@@ -1375,6 +1375,9 @@ class RestApiServer(ThreadingMixIn, HTTPServer, Thread):
     def query(self, sql: str, *params: Any) -> List[Tuple[Any, ...]]:
         """Execute *sql* query with *params* and optionally return results.
 
+        .. note::
+            Prefer to use own connection to postgres and fallback to ``heartbeat`` when own isn't available.
+
         :param sql: the SQL statement to be run.
         :param params: positional arguments to be used as parameters for *sql*.
 
@@ -1384,10 +1387,21 @@ class RestApiServer(ThreadingMixIn, HTTPServer, Thread):
             :class:`psycopg.Error`: if had issues while executing *sql*.
             :class:`~patroni.exceptions.PostgresConnectionException`: if had issues while connecting to the database.
         """
+        # We first try to get a heartbeat connection because it is always required for the main thread.
         try:
-            return self.patroni.postgresql.query(sql, *params, retry=False)
-        except RetryFailedError as e:
-            raise PostgresConnectionException(str(e))
+            heartbeat_connection = self.patroni.postgresql.connection_pool.get('heartbeat')
+            heartbeat_connection.get()  # try to open psycopg connection to postgres
+        except psycopg.Error as exc:
+            raise PostgresConnectionException('connection problems') from exc
+
+        try:
+            connection = self.patroni.postgresql.connection_pool.get('restapi')
+            connection.get()  # try to open psycopg connection to postgres
+        except psycopg.Error:
+            logger.debug('restapi connection to postgres is not available')
+            connection = heartbeat_connection
+
+        return connection.query(sql, *params)
 
     @staticmethod
     def _set_fd_cloexec(fd: socket.socket) -> None:
diff --git a/tests/test_api.py b/tests/test_api.py
index f433ca18..fa9a6280 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -11,9 +11,12 @@ from socketserver import ThreadingMixIn
 from patroni.api import RestApiHandler, RestApiServer
 from patroni.config import GlobalConfig
 from patroni.dcs import ClusterConfig, Member
+from patroni.exceptions import PostgresConnectionException
 from patroni.ha import _MemberStatus
+from patroni.psycopg import OperationalError
 from patroni.utils import RetryFailedError, tzutc
 
+from . import MockConnect, psycopg_connect
 from .test_ha import get_cluster_initialized_without_leader
 
 
@@ -21,8 +24,29 @@ future_restart_time = datetime.datetime.now(tzutc) + datetime.timedelta(days=5)
 postmaster_start_time = datetime.datetime.now(tzutc)
 
 
-class MockPostgresql(object):
+class MockConnection:
 
+    @staticmethod
+    def get(*args):
+        return psycopg_connect()
+
+    @staticmethod
+    def query(sql, *params):
+        return [(postmaster_start_time, 0, '', 0, '', False, postmaster_start_time, 'streaming', None,
+                 '[{"application_name":"walreceiver","client_addr":"1.2.3.4",'
+                 + '"state":"streaming","sync_state":"async","sync_priority":0}]')]
+
+
+class MockConnectionPool:
+
+    @staticmethod
+    def get(*args):
+        return MockConnection()
+
+
+class MockPostgresql:
+
+    connection_pool = MockConnectionPool()
     name = 'test'
     state = 'running'
     role = 'primary'
@@ -54,12 +78,6 @@ class MockPostgresql(object):
     def replication_state_from_parameters(*args):
         return 'streaming'
 
-    @staticmethod
-    def query(sql, *params, retry=False):
-        return [(postmaster_start_time, 0, '', 0, '', False, postmaster_start_time, 'streaming', None,
-                 '[{"application_name":"walreceiver","client_addr":"1.2.3.4",'
-                 + '"state":"streaming","sync_state":"async","sync_priority":0}]')]
-
 
 class MockWatchdog(object):
     is_healthy = False
@@ -487,7 +505,7 @@ class TestRestApiHandler(unittest.TestCase):
 
     @patch('time.sleep', Mock())
     def test_RestApiServer_query(self):
-        with patch.object(MockPostgresql, 'query', Mock(side_effect=RetryFailedError('bla'))):
+        with patch.object(MockConnection, 'query', Mock(side_effect=RetryFailedError('bla'))):
             self.assertIsNotNone(MockRestApiServer(RestApiHandler, 'GET /patroni'))
 
     @patch('time.sleep', Mock())
@@ -659,3 +677,11 @@ class TestRestApiServer(unittest.TestCase):
 
     def test_get_certificate_serial_number(self):
         self.assertIsNone(self.srv.get_certificate_serial_number())
+
+    def test_query(self):
+        with patch.object(MockConnection, 'get', Mock(side_effect=OperationalError)):
+            self.assertRaises(PostgresConnectionException, self.srv.query, 'SELECT 1')
+        with patch.object(MockConnection, 'get', Mock(side_effect=[MockConnect(), OperationalError])), \
+                patch.object(MockConnection, 'query') as mock_query:
+            self.srv.query('SELECT 1')
+            mock_query.assert_called_once_with('SELECT 1')