tuning import process and db handling

app/__init__.py

@@ -18,6 +18,21 @@ def create_app(config_class='config.Config'):
     login_manager.init_app(app)
     login_manager.login_view = 'auth.login'
 
+    with app.app_context():
+        # Enable connection ping only for PostgreSQL
+        if app.config['SQLALCHEMY_DATABASE_URI'].startswith("postgresql"):
+            from sqlalchemy import event, text
+            from sqlalchemy.exc import DisconnectionError
+
+            @event.listens_for(db.engine, "engine_connect")
+            def ping_connection(connection, branch):
+                if branch:
+                    return
+                try:
+                    connection.execution_options(isolation_level="AUTOCOMMIT").scalar(text("SELECT 1"))
+                except:
+                    raise DisconnectionError()
+
     from app.main import main
     from app.auth import auth
 
@@ -28,5 +43,4 @@ def create_app(config_class='config.Config'):
     def datetimeformat(value, format="%Y-%m-%d"):
         return value.strftime(format) if value else ""
 
-
     return app