Commit 9f6a82fa authored by Russell Keith-Magee's avatar Russell Keith-Magee
Browse files

Fixed #13156 -- Ensure that exists() queries are as fast as they can be.... 

Fixed #13156 -- Ensure that exists() queries are as fast as they can be. Thanks to Jerome Leclanche for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12810 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent d58020fc

django/db/models/sql/query.py

+5 −2
Original line number Diff line number Diff line
@@ -377,10 +377,13 @@ class Query(object): 
    def has_results(self, using):

        q = self.clone()

        q.add_extra({'a': 1}, None, None, None, None, None)

        q.add_fields(())

        q.select = []

        q.select_fields = []

        q.default_cols = False

        q.select_related = False

        q.set_extra_mask(('a',))

        q.set_aggregate_mask(())

        q.clear_ordering()

        q.clear_ordering(True)

        q.set_limits(high=1)

        compiler = q.get_compiler(using=using)

        return bool(compiler.execute_sql(SINGLE))

tests/regressiontests/queries/models.py

+10 −0
Original line number Diff line number Diff line
@@ -277,6 +277,16 @@ class Plaything(models.Model): 




__test__ = {'API_TESTS':"""

>>> # Regression for #13156 -- exists() queries have minimal SQL

>>> from django.db import connection

>>> settings.DEBUG = True

>>> Tag.objects.exists()

False

>>> # Ok - so the exist query worked - but did it include too many columns?

>>> "id" not in connection.queries[-1]['sql'] and "name" not in connection.queries[-1]['sql']

True

>>> settings.DEBUG = False



>>> generic = NamedCategory.objects.create(name="Generic")

>>> t1 = Tag.objects.create(name='t1', category=generic)

>>> t2 = Tag.objects.create(name='t2', parent=t1, category=generic)