Here's the ticket: https://code.djangoproject.com/ticket/6785
tl;dr: Calling .get() on a badly filtered queryset can result in lots of database rows being fetched and wrapped in Python objects for no gain. Currently .get() logic is as follows: clone the queryset, prepopulate its full cache, check if more than one row was returned and if so, raise MultipleObjectsReturned. This works fine if the query returns two or five rows. It's not so fine if the query results in thousands or millions of rows being returned. While working on a large online store we had one of the production servers die while trying to fetch twenty something million rows because of a programming error that resulted in wrong Q object being used as a filter. The only reason all rows are fetched is to return an accurate counter as part of the exception message. This counter is not accessible programmatically and having the exact number there is of little value. The ticket proposes to add a safeguard by limiting the database to at most two results. The logic then is simple: if zero rows are returned, raise ObjectDoesNotExist, if two, raise MultipleObjectsReturned. The latter could possibly execute a second COUNT query if DEBUG is enabled and the counter is deemed important enough to keep. Of course you can work around the whole problem by not writing buggy code but we all know how it works. In the mentioned case even unit tests did not help as there were not enough records in the database to trigger MultipleObjectsReturned. Related pull request: https://github.com/django/django/pull/1139 -- Patryk Zawadzki I solve problems. -- You received this message because you are subscribed to the Google Groups "Django developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at http://groups.google.com/group/django-developers?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
