#9 - optimization: fetch first measurement from database and use this as min...

#9 - optimization: fetch first measurement from database and use this as min date instead of 01.01.1970

src/logic/database/Crud.py

@@ -137,6 +137,13 @@ def get_latest_measurement_for_sensor(db: Session, sensorId: int) -> Models.Meas
         .first()
 
 
+def get_first_measurement_for_sensor(db: Session, sensorId: int) -> Models.Measurement:
+    return db.query(Models.Measurement) \
+        .filter(Models.Measurement.sensor_id == sensorId) \
+        .order_by(Models.Measurement.timestamp.asc()) \
+        .first()
+
+
 def get_measurement(db: Session, measurementId: int) -> Models.Measurement:
     return db.query(Models.Measurement).filter(Models.Measurement.id == measurementId).first()
 

src/logic/database/DatabaseCleaner.py

@@ -30,8 +30,14 @@ class DatabaseCleaner:
                 LOGGER.debug(f'Cleaning measurements for sensor "{sensor.name}" '
                              f'(id: {sensor.id}, device_id: {sensor.device_id})')
 
+                firstMeasurement = Crud.get_first_measurement_for_sensor(db=db, sensorId=sensor.id)
+                if firstMeasurement is None:
+                    continue
+
+                minDate = datetime.strptime(firstMeasurement.timestamp, Crud.DATE_FORMAT).date()
+
                 processedDate = policyStart
-                while processedDate > self.MIN_DATE:
+                while processedDate > minDate:
                     LOGGER.debug(f'Cleaning {processedDate.strftime("%Y-%m-%d")}...')
                     measurementIds, idsToDelete = DatabaseCleaner._categorize_measurements_for_day(db,
                                                                                                    date=processedDate,

src/test/DatabaseCleanerTest.py

@@ -58,6 +58,10 @@ class TestRetentionPolicy(unittest.TestCase):
 
 
 class TestDatabaseCleaner(unittest.TestCase):
+    FIRST_MEASUREMENT = Schemas.Measurement(id=0, value=18, sensor_id=1,
+                                            timestamp=datetime(year=2021, month=8, day=1,
+                                                               hour=22, minute=45, second=0).strftime(DATE_FORMAT))
+
     MEASUREMENT1 = Schemas.Measurement(id=1, value=5, sensor_id=1,
                                        timestamp=datetime(year=2021, month=8, day=18,
                                                           hour=6, minute=55, second=0).strftime(DATE_FORMAT))
@@ -225,6 +229,7 @@ class TestDatabaseCleaner(unittest.TestCase):
             mockedCrud.get_measurements_for_sensor.side_effect = self.get_measurements_mocked
             mockedCrud.get_sensors.return_value = [Schemas.Sensor(id=1, name="myTempSensor",
                                                                   type="temperature", device_id=1)]
+            mockedCrud.get_first_measurement_for_sensor.return_value = self.FIRST_MEASUREMENT
 
             database = Mock()
             from logic.database.DatabaseCleaner import DatabaseCleaner
@@ -235,6 +240,9 @@ class TestDatabaseCleaner(unittest.TestCase):
 
             mockedCrud.delete_multiple_measurements.assert_called_once_with(database, {3})
 
+            calls = mockedCrud.get_measurements_for_sensor.call_args_list
+            self.assertNotIn((database, '2020-01-01 00:00:00', '2020-01-01 06:00:00', 1), [call.args for call in calls])
+
     def test_onePolicy_deleteMeasurements_twoSensors(self):
         mockedCrud = Mock()
         with patch.dict('sys.modules', **{'logic.database.Crud': mockedCrud}):
@@ -244,6 +252,7 @@ class TestDatabaseCleaner(unittest.TestCase):
                                                                   type="temperature", device_id=1),
                                                    Schemas.Sensor(id=2, name="myHumiditySensor",
                                                                   type="humidity", device_id=1)]
+            mockedCrud.get_first_measurement_for_sensor.return_value = self.FIRST_MEASUREMENT
 
             database = Mock()
             from logic.database.DatabaseCleaner import DatabaseCleaner
@@ -257,5 +266,4 @@ class TestDatabaseCleaner(unittest.TestCase):
             self.assertEqual((database, {3}), calls[0].args)
             self.assertEqual((database, {5}), calls[1].args)
 
-
             # TODO: test: multiple policies