[FIX] point_of_sale : add index

In large database, to compute picking_count on orders and sessions, can take lot of time.

closes odoo/odoo#115446

X-original-commit: 59d3377e
Signed-off-by: Trinh Jacky (trj) <trj@odoo.com>

addons/point_of_sale/models/stock_picking.py

@@ -11,8 +11,8 @@ from collections import defaultdict
 class StockPicking(models.Model):
     _inherit='stock.picking'
 
-    pos_session_id = fields.Many2one('pos.session')
-    pos_order_id = fields.Many2one('pos.order')
+    pos_session_id = fields.Many2one('pos.session', index=True)
+    pos_order_id = fields.Many2one('pos.order', index=True)
 
     def _prepare_picking_vals(self, partner, picking_type, location_id, location_dest_id):
         return {