diff --git a/addons/point_of_sale/models/pos_order.py b/addons/point_of_sale/models/pos_order.py
index 1631cf2fa4e..26ff5c35914 100644
--- a/addons/point_of_sale/models/pos_order.py
+++ b/addons/point_of_sale/models/pos_order.py
@@ -898,7 +898,7 @@ class PosOrderLine(models.Model):
     total_cost = fields.Float(string='Total cost', digits='Product Price', readonly=True)
     is_total_cost_computed = fields.Boolean(help="Allows to know if the total cost has already been computed or not")
     discount = fields.Float(string='Discount (%)', digits=0, default=0.0)
-    order_id = fields.Many2one('pos.order', string='Order Ref', ondelete='cascade', required=True)
+    order_id = fields.Many2one('pos.order', string='Order Ref', ondelete='cascade', required=True, index=True)
     tax_ids = fields.Many2many('account.tax', string='Taxes', readonly=True)
     tax_ids_after_fiscal_position = fields.Many2many('account.tax', compute='_get_tax_ids_after_fiscal_position', string='Taxes to Apply')
     pack_lot_ids = fields.One2many('pos.pack.operation.lot', 'pos_order_line_id', string='Lot/serial Number')