From dd23cf40e116dc1531d915a03a0bd2fcfc686563 Mon Sep 17 00:00:00 2001
From: Mihir Kandoi <kandoimihir@gmail.com>
Date: Tue, 11 Aug 2026 12:27:22 +0530
Subject: [PATCH] perf(selling): batch billed quantity lookup

---
 erpnext/selling/doctype/sales_order/mapper.py | 28 +++++++++++------
 .../doctype/sales_order/test_sales_order.py   | 30 +++++++++++++++++++
 2 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/erpnext/selling/doctype/sales_order/mapper.py b/erpnext/selling/doctype/sales_order/mapper.py
index fecf67cc642..06635b97088 100644
--- a/erpnext/selling/doctype/sales_order/mapper.py
+++ b/erpnext/selling/doctype/sales_order/mapper.py
@@ -441,25 +441,35 @@ def make_sales_invoice(
 
 	# 0 qty is accepted, as the qty is uncertain for some items
 	has_unit_price_items = frappe.db.get_value("Sales Order", source_name, "has_unit_price_items")
+	billed_qty_by_item = None
 	pending_qty_by_item = {}
 
 	def is_unit_price_row(source):
 		return has_unit_price_items and source.qty == 0
 
-	def get_billed_qty(so_item_name):
-		table = frappe.qb.DocType("Sales Invoice Item")
-		query = (
-			frappe.qb.from_(table)
-			.select(Sum(table.qty).as_("qty"))
-			.where((table.docstatus == 1) & (table.so_detail == so_item_name))
-		)
-		return flt(query.run(pluck="qty")[0])
+	def get_billed_qty_by_item():
+		nonlocal billed_qty_by_item
+
+		if billed_qty_by_item is None:
+			invoice_item = frappe.qb.DocType("Sales Invoice Item")
+			sales_order_item = frappe.qb.DocType("Sales Order Item")
+			rows = (
+				frappe.qb.from_(invoice_item)
+				.inner_join(sales_order_item)
+				.on(invoice_item.so_detail == sales_order_item.name)
+				.select(invoice_item.so_detail, Sum(invoice_item.qty).as_("qty"))
+				.where((invoice_item.docstatus == 1) & (sales_order_item.parent == source_name))
+				.groupby(invoice_item.so_detail)
+			).run(as_dict=True)
+			billed_qty_by_item = {row.so_detail: flt(row.qty) for row in rows}
+
+		return billed_qty_by_item
 
 	def get_pending_qty(source):
 		if source.name not in pending_qty_by_item:
 			billable_qty = get_qty_net_of_returns(source)
 			if source.qty and source.billed_amt:
-				billable_qty -= get_billed_qty(source.name)
+				billable_qty -= get_billed_qty_by_item().get(source.name, 0)
 
 			pending_qty_by_item[source.name] = max(flt(billable_qty), 0)
 
diff --git a/erpnext/selling/doctype/sales_order/test_sales_order.py b/erpnext/selling/doctype/sales_order/test_sales_order.py
index eb5bb6495cc..2dd1a73dea6 100644
--- a/erpnext/selling/doctype/sales_order/test_sales_order.py
+++ b/erpnext/selling/doctype/sales_order/test_sales_order.py
@@ -347,6 +347,36 @@ class TestSalesOrder(ERPNextTestSuite):
 		so.load_from_db()
 		self.assertEqual(so.get("items")[0].billed_amt, 500)
 
+	def test_make_sales_invoice_after_partial_billing_multiple_items(self):
+		so = make_sales_order(
+			item_list=[
+				{
+					"item_code": "_Test Item",
+					"warehouse": "_Test Warehouse - _TC",
+					"qty": 10,
+					"rate": 100,
+				},
+				{
+					"item_code": "_Test FG Item",
+					"warehouse": "_Test Warehouse - _TC",
+					"qty": 10,
+					"rate": 100,
+				},
+			]
+		)
+
+		si = make_sales_invoice(so.name)
+		si.get("items")[0].qty = 4
+		si.get("items")[1].qty = 6
+		si.insert()
+		si.submit()
+
+		pending_invoice = make_sales_invoice(so.name)
+		self.assertEqual(
+			{item.so_detail: item.qty for item in pending_invoice.get("items")},
+			{so.get("items")[0].name: 6, so.get("items")[1].name: 4},
+		)
+
 	def test_so_billed_amount_against_return_entry(self):
 		from erpnext.accounts.doctype.sales_invoice.mapper import make_sales_return