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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
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commit 9f6a82fafbd84865a06e162c14b6a5d5e110babe 1 parent d58020f
@freakboy3742 freakboy3742 authored
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7 django/db/models/sql/query.py
@@ -377,10 +377,13 @@ def get_count(self, using):
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))
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10 tests/regressiontests/queries/models.py
@@ -277,6 +277,16 @@ def __unicode__(self):
__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)
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