django-pyodbc-azure SQL Server参数限制

时间：2018-12-19 18:10:24

标签： python sql-server django django-pyodbc django-pyodbc-azure

Django：1.11

我使用django-pyodbc-azure作为Django后端。它正在连接到SQL Server2012。SQLServer的参数限制为2100个。当我尝试在查询集上使用prefetch_related时，该查询集将返回2100多个结果... 

def object_search_list(request):
    objects = MyModel.objects.filter(some_field='filter value').select_related('another_field').prefetch_related('a_third_field')
    print(objects)
    return render(request, 'objects/object_list.html', {'objects':objects})

...此错误返回：

Exception Value: ('07002', '[07002] [Microsoft][SQL Server Native Client 11.0]COUNT field incorrect or syntax error (0) (SQLExecDirectW)')

它指向django-pyodbc-azure使用的pyodbc后端。查看功能（https://github.com/michiya/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py）时，没有设置max_query_params。我试图手动添加max_query_params = 2100。这导致了同样的错误。将该值设置为2000和1000也会导致相同的错误。

如何调整django-pyodbc-azure以自动处理此SQL Server限制？

针对Django的Oracle后端具有类似以下功能：https://github.com/django/django/blob/master/django/db/backends/oracle/features.py

更新：

我意识到max_query_params是Django 2.0的新名称。因此，我尝试使用max_limit_in_size来匹配Django 1.11。仅仅是django-pyodbc-azure不支持控制参数计数，而base.py会覆盖Django的默认base.py吗？

更新2：

我升级到Django 2.1，并升级了django-pyodbc-azure以匹配。然后，我编辑了features.py，将max_query_params = 2000添加为功能。 max_query_params在Django本机后端中出现的另一个地方是此函数中的operations.py（Oracle示例）：

def bulk_batch_size(self, fields, objs):
    """Oracle restricts the number of parameters in a query."""
    if fields:
        return self.connection.features.max_query_params // len(fields)
    return len(objs)

django-pyodbc-azure也具有此功能，看起来像这样：

def bulk_batch_size(self, fields, objs):
    """
    Returns the maximum allowed batch size for the backend. The fields
    are the fields going to be inserted in the batch, the objs contains
    all the objects to be inserted.
    """
    objs_len, fields_len, max_row_values = len(objs), len(fields), 1000
    if (objs_len * fields_len) <= max_row_values:
        size = objs_len
    else:
        size = max_row_values // fields_len
    return size

看来max_row_values设置为1000时已经可以进行批处理了。但是，相同的错误仍然存​​在。我也尝试将1000更改为max_query_params无济于事。

这是完整的追溯：

Traceback:

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\sql_server\pyodbc\base.py" in execute
  546.             return self.cursor.execute(sql, params)

The above exception (('07002', '[07002] [Microsoft][SQL Server Native Client 11.0]COUNT field incorrect or syntax error (0) (SQLExecDirectW)')) was the direct cause of the following exception:

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\exception.py" in inner
  34.             response = get_response(request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\base.py" in _get_response
  126.                 response = self.process_exception_by_middleware(e, request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\base.py" in _get_response
  124.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
  21.                 return view_func(request, *args, **kwargs)

File "C:\Users\user\djangoproject\app\views.py" in object_list
  486.     return render(request, 'objects/object_list.html', {'objects':objects})

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\shortcuts.py" in render
  36.     content = loader.render_to_string(template_name, context, request, using=using)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader.py" in render_to_string
  62.     return template.render(context, request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\backends\django.py" in render
  61.             return self.template.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  171.                     return self._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  150.             return compiled_parent._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  62.                 result = block.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  188.             return template.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  173.                 return self._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\defaulttags.py" in render
  166.             len_values = len(values)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __len__
  250.         self._fetch_all()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _fetch_all
  1188.             self._prefetch_related_objects()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _prefetch_related_objects
  723.         prefetch_related_objects(self._result_cache, *self._prefetch_related_lookups)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in prefetch_related_objects
  1569.                 obj_list, additional_lookups = prefetch_one_level(obj_list, prefetcher, lookup, level)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in prefetch_one_level
  1699.     all_related_objects = list(rel_qs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __iter__
  268.         self._fetch_all()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _fetch_all
  1186.             self._result_cache = list(self._iterable_class(self))

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __iter__
  54.         results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\sql\compiler.py" in execute_sql
  1065.             cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\debug_toolbar\panels\sql\tracking.py" in execute
  186.         return self._record(self.cursor.execute, sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\debug_toolbar\panels\sql\tracking.py" in _record
  124.             return method(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in execute
  100.             return super().execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in execute
  68.         return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute_with_wrappers
  77.         return executor(sql, params, many, context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\utils.py" in __exit__
  89.                 raise dj_exc_value.with_traceback(traceback) from exc_value

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\sql_server\pyodbc\base.py" in execute
  546.             return self.cursor.execute(sql, params)

Exception Type: Error at url
Exception Value: ('07002', '[07002] [Microsoft][SQL Server Native Client 11.0]COUNT field incorrect or syntax error (0) (SQLExecDirectW)')

1 个答案:

答案 0 :(得分：1)

它似乎没有被添加到django-pyodbc-azure中：

https://github.com/michiya/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py#L4

我已将其添加到我的叉子中

https://github.com/FlipperPA/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py#L33

您能给它做个测试吗？您需要升级到Django 2.1，然后应该能够pip install git+https://github.com/FlipperPA/django-pyodbc-azure.git@azure-2.1来查看它是否和添加该设置一样简单。粗略地看一下Django的源代码，看起来这可能就是全部。如果可行，我将向Michaya发出拉取请求。

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