diff options
| author | Luke Plant <L.Plant.98@cantab.net> | 2011-10-08 13:50:29 +0000 |
|---|---|---|
| committer | Luke Plant <L.Plant.98@cantab.net> | 2011-10-08 13:50:29 +0000 |
| commit | d5803bb5fb1a301a014bb681fedc09e2bcc6967b (patch) | |
| tree | 3e44f111ec18c50e1ff19f922e3bda710f6923e5 /django/db | |
| parent | 095dbe8804d89785b59ef0cd0381a31b31a2dab5 (diff) | |
More efficient IN clauses for prefetch_related queries by use of sets to eliminate duplicates
This simply reduces the size of the IN clause in the SQL, which can be
significant in some cases.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@16944 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Diffstat (limited to 'django/db')
| -rw-r--r-- | django/db/models/fields/related.py | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py index c82c397288..8c054e7303 100644 --- a/django/db/models/fields/related.py +++ b/django/db/models/fields/related.py @@ -237,7 +237,7 @@ class SingleRelatedObjectDescriptor(object): return self.related.model._base_manager.using(db) def get_prefetch_query_set(self, instances): - vals = [instance._get_pk_val() for instance in instances] + vals = set(instance._get_pk_val() for instance in instances) params = {'%s__pk__in' % self.related.field.name: vals} return (self.get_query_set(), attrgetter(self.related.field.attname), @@ -316,7 +316,7 @@ class ReverseSingleRelatedObjectDescriptor(object): return QuerySet(self.field.rel.to).using(db) def get_prefetch_query_set(self, instances): - vals = [getattr(instance, self.field.attname) for instance in instances] + vals = set(getattr(instance, self.field.attname) for instance in instances) other_field = self.field.rel.get_related_field() if other_field.rel: params = {'%s__pk__in' % self.field.rel.field_name: vals} @@ -463,7 +463,7 @@ class ForeignRelatedObjectsDescriptor(object): def get_prefetch_query_set(self, instances): db = self._db or router.db_for_read(self.model) query = {'%s__%s__in' % (rel_field.name, attname): - [getattr(obj, attname) for obj in instances]} + set(getattr(obj, attname) for obj in instances)} qs = super(RelatedManager, self).get_query_set().using(db).filter(**query) return (qs, attrgetter(rel_field.get_attname()), @@ -546,7 +546,7 @@ def create_many_related_manager(superclass, rel): from django.db import connections db = self._db or router.db_for_read(self.model) query = {'%s__pk__in' % self.query_field_name: - [obj._get_pk_val() for obj in instances]} + set(obj._get_pk_val() for obj in instances)} qs = super(ManyRelatedManager, self).get_query_set().using(db)._next_is_sticky().filter(**query) # M2M: need to annotate the query in order to get the primary model |