Commit 08d14925 authored by Ramiro Morales's avatar Ramiro Morales
Browse files

Fixed #12192 -- Don't execute any DB query when the QS slicing being performed 

will result in use of LIMIT 0. Thanks Suor for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14204 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 5f5a61e7

django/db/backends/oracle/compiler.py

+2 −0
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ class SQLCompiler(compiler.SQLCompiler): 
        If 'with_limits' is False, any limit/offset information is not

        included in the query.

        """

        if with_limits and self.query.low_mark == self.query.high_mark:

            return '', ()



        # The `do_offset` flag indicates whether we need to construct

        # the SQL needed to use limit/offset with Oracle.

django/db/models/sql/compiler.py

+3 −0
Original line number Diff line number Diff line
@@ -52,6 +52,9 @@ class SQLCompiler(object): 
        If 'with_limits' is False, any limit/offset information is not included

        in the query.

        """

        if with_limits and self.query.low_mark == self.query.high_mark:

            return '', ()



        self.pre_sql_setup()

        out_cols = self.get_columns(with_col_aliases)

        ordering, ordering_group_by = self.get_ordering()

tests/regressiontests/queries/tests.py

+11 −1
Original line number Diff line number Diff line
@@ -91,3 +91,13 @@ class EmptyQuerySetTests(TestCase): 
        self.assertQuerysetEqual(

            Number.objects.filter(pk__in=Number.objects.none().values("pk")), []

        )





class WeirdQuerySetSlicing(TestCase):

    def setUp(self):

        Number.objects.create(num=1)

        Number.objects.create(num=2)



    def test_empty_resultset_sql(self):

        # ticket #12192

        self.assertNumQueries(0, lambda: list(Number.objects.all()[1:1]))