fix: auto add modified index when sort_field is set to it (backport #…

…25686) (#25785)

* fix: auto add modified index when sort_field is set to it (#25686)

This is 2nd most common sort order, so we should support adding index
for it automatically.

Not quite sure on generalizing this behaviour *YET*

(cherry picked from commit 67bcda3)

# Conflicts:
#	frappe/database/mariadb/schema.py
#	frappe/email/smtp.py

* fix: v15 compat

modified is default, creation is optional on v15

* chore: conflicts

---------

Co-authored-by: Ankush Menat <ankush@frappe.io>

frappe/database/mariadb/schema.py

@@ -90,6 +90,11 @@ def alter(self):
 			if not frappe.db.get_column_index(self.table_name, col.fieldname, unique=False):
 				add_index_query.append(f"ADD INDEX `{col.fieldname}_index`(`{col.fieldname}`)")
 
+		if self.meta.sort_field == "creation" and frappe.db.get_column_index(
+			self.table_name, "creation", unique=False
+		):
+			add_index_query.append("ADD INDEX `creation`(`creation`)")
+
 		for col in {*self.drop_index, *self.drop_unique}:
 			if col.fieldname == "name":
 				continue