This join is a leftover from https://github.com/odoo/odoo/pull/28248 and is not needed anymore since currency_rate is now stored on purchase.order. Removing it allows to greatly speedup purchase.report queries. On a database with 7000 purchase order and 1100 res_currency_rate: From: Planning Time: 4.411 ms Execution Time: 19815.754 ms To: Planning Time: 16.914 ms Execution Time: 77.433 ms opw-2973044 closes odoo/odoo#104301 X-original-commit: 4ffa967eecfd930da7a0051122ed746af38ce709 Signed-off-by: Arnold Moyaux (arm) <arm@odoo.com>