more refactor

anaxi/sync.py

@@ -11,6 +11,7 @@ from anaxi.config import (
 )
 from anaxi.constants import (
     ASSUMED_PREHISTORICAL_DATETIME,
+    COSMOS_DB_TIMESTAMP_FIELD_KEY,
     DEFAULT_BATCH_SIZE,
     DESTINATION_COLUMN_NAME,
     PATHS,
@@ -94,7 +95,9 @@ class SyncJob:
 
     def commit_batch(self, docs_batch, cursor):
         self.checkpoint_manager.set_new_goal(
-            goal_timestamp=datetime.datetime.fromtimestamp(docs_batch[-1]["_ts"])
+            goal_timestamp=datetime.datetime.fromtimestamp(
+                docs_batch[-1][COSMOS_DB_TIMESTAMP_FIELD_KEY]
+            )
         )
 
         json_data = [(json.dumps(d),) for d in docs_batch]