id summary reporter owner description type status component version severity resolution keywords cc stage has_patch needs_docs needs_tests needs_better_patch easy ui_ux 17990 DISTINCT querysets with RANDOM ordering crash with DatabaseError in Postgres Paul Bailey Ryan Cheley "When using distinct().order_by('?') with Postgres you get a query error. My models: {{{ class Category (models.Model): title = models.CharField(max_length=100) slug = models.SlugField(unique=True, max_length=200) class Post (models.Model): title = models.CharField(max_length=255) slug = models.SlugField(unique=True, max_length=200) publish = models.DateTimeField() categories = models.ManyToManyField(Category) body = models.TextField() }}} Causes Bug in Postgres but not SQLite: {{{ return Post.objects.filter(categories__in=cats).exclude(id=self.id).order_by('?').distinct()[:5] }}} No Error: {{{ return Post.objects.filter(categories__in=cats).exclude(id=self.id).distinct()[:5] }}} Traceback: {{{ ERROR:django.request:Internal Server Error: /blog/online-photo-editors/ Traceback (most recent call last): File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/core/handlers/base.py"", line 136, in get_response response = response.render() File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/response.py"", line 104, in render self._set_content(self.rendered_content) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/response.py"", line 81, in rendered_content content = template.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 140, in render return self._render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 134, in _render return self.nodelist.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 823, in render bit = self.render_node(node, context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 837, in render_node return node.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/loader_tags.py"", line 123, in render return compiled_parent._render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 134, in _render return self.nodelist.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 823, in render bit = self.render_node(node, context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 837, in render_node return node.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/loader_tags.py"", line 62, in render result = block.nodelist.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 823, in render bit = self.render_node(node, context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/base.py"", line 837, in render_node return node.render(context) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/template/defaulttags.py"", line 145, in render len_values = len(values) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/db/models/query.py"", line 85, in __len__ self._result_cache = list(self.iterator()) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/db/models/query.py"", line 291, in iterator for row in compiler.results_iter(): File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py"", line 763, in results_iter for rows in self.execute_sql(MULTI): File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py"", line 818, in execute_sql cursor.execute(sql, params) File ""/home/webapp/pyenv/cr/local/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py"", line 52, in execute return self.cursor.execute(query, args) DatabaseError: for SELECT DISTINCT, ORDER BY expressions must appear in select list LINE 1: ..."" = 4 ) AND NOT (""blog_post"".""id"" = 4 )) ORDER BY RANDOM() L... }}} " Bug closed Database layer (models, ORM) 1.4 Normal duplicate Étienne Beaulé Accepted 0 0 0 0 0 0