谢谢@solarissmoke指向 connection.queries 。

我期待看到

  SELECT DISTINCT refdate FROM myTable 
 

相反，我有

  SELECT DISTINCT refdate，itemIndex，itemType FROM myTable ORDER BY itemIndex，refdate，itemType。 
 

然后我看看在 models.py $ c $中定义的myTable c>。

  unique_together =（（'nodeIndex'，'refdate'，'nodeType'），）
 = ['nodeIndex'，'refdate'，'nodeType'] 
 

从与默认排序或order_by的交互

通常你不会想要额外的列在结果中播放一部分，所以清除订购，或者至少确保它被限制

所以我试过 order_by（）来刷新以前定义的顺序和瞧瞧！

  myTable.objects.values（'refdate'）。 order_by（）。distinct（）
 

I have a MySQL table with 13M rows. I can query the db directly as

SELECT DISTINCT(refdate) FROM myTable

The query takes 0.15 seconds and is great.

The equivalent table defined as a Django model and queried as

myTable.objects.values(`refdate`).distinct()

takes a very long time. Is it because there are too many items in the list before distinct(). How do I do this in a manner that doesn't bring everything down?

Thank you @solarissmoke for the pointer to connection.queries.

I was expecting to see

SELECT DISTINCT refdate FROM myTable

Instead, I got

SELECT DISTINCT refdate, itemIndex, itemType FROM myTable ORDER BY itemIndex, refdate, itemType. 

I then looked at myTable defined in models.py.

unique_together = (('nodeIndex', 'refdate', 'nodeType'), )
ordering = ['nodeIndex', 'refdate', 'nodeType']

From Interaction with default ordering or order_by

normally you won’t want extra columns playing a part in the result, so clear out the ordering, or at least make sure it’s restricted only to those fields you also select in a values() call.

So I tried order_by() to flush the previously defined ordering and voila!

myTable.objects.values('refdate').order_by().distinct()