Fixed #23147 -- Disabled a limit/offset on a query with select_for_update on Oracle.

Thanks Shai Berger and Tim Graham for the reviews.

django/db/backends/oracle/compiler.py

@@ -1,3 +1,4 @@
+from django.db import NotSupportedError
 from django.db.models.sql import compiler
 
 
@@ -17,6 +18,11 @@ class SQLCompiler(compiler.SQLCompiler):
         do_offset = with_limits and (self.query.high_mark is not None or self.query.low_mark)
         if not do_offset:
             sql, params = super().as_sql(with_limits=False, with_col_aliases=with_col_aliases)
+        elif not self.connection.features.supports_select_for_update_with_limit and self.query.select_for_update:
+            raise NotSupportedError(
+                'LIMIT/OFFSET not supported with select_for_update on this '
+                'database backend.'
+            )
         else:
             sql, params = super().as_sql(with_limits=False, with_col_aliases=True)
             # Wrap the base query in an outer SELECT * with boundaries on

django/db/models/sql/compiler.py

@@ -10,7 +10,7 @@ from django.db.models.sql.constants import (
 )
 from django.db.models.sql.query import Query, get_order_dir
 from django.db.transaction import TransactionManagementError
-from django.db.utils import DatabaseError
+from django.db.utils import DatabaseError, NotSupportedError
 
 FORCE = object()
 
@@ -460,6 +460,11 @@ class SQLCompiler:
                     if self.connection.get_autocommit():
                         raise TransactionManagementError('select_for_update cannot be used outside of a transaction.')
 
+                    if with_limits and not self.connection.features.supports_select_for_update_with_limit:
+                        raise NotSupportedError(
+                            'LIMIT/OFFSET not supported with select_for_update'
+                            ' on this database backend.'
+                        )
                     nowait = self.query.select_for_update_nowait
                     skip_locked = self.query.select_for_update_skip_locked
                     # If it's a NOWAIT/SKIP LOCKED query but the backend

tests/select_for_update/tests.py

@@ -5,7 +5,8 @@ from unittest import mock
 from multiple_database.routers import TestRouter
 
 from django.db import (
-    DatabaseError, connection, connections, router, transaction,
+    DatabaseError, NotSupportedError, connection, connections, router,
+    transaction,
 )
 from django.test import (
     TransactionTestCase, override_settings, skipIfDBFeature,
@@ -179,6 +180,20 @@ class SelectForUpdateTests(TransactionTestCase):
         with self.assertRaises(transaction.TransactionManagementError):
             list(people)
 
+    @skipUnlessDBFeature('supports_select_for_update_with_limit')
+    def test_select_for_update_with_limit(self):
+        other = Person.objects.create(name='Grappeli')
+        with transaction.atomic():
+            qs = list(Person.objects.all().order_by('pk').select_for_update()[1:2])
+            self.assertEqual(qs[0], other)
+
+    @skipIfDBFeature('supports_select_for_update_with_limit')
+    def test_unsupported_select_for_update_with_limit(self):
+        msg = 'LIMIT/OFFSET not supported with select_for_update on this database backend.'
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            with transaction.atomic():
+                list(Person.objects.all().order_by('pk').select_for_update()[1:2])
+
     def run_select_for_update(self, status, **kwargs):
         """
         Utility method that runs a SELECT FOR UPDATE against all