Specifying limit and offset in Django QuerySet wont work

Question

I'm using Django 1.6.5 and have MySQL's general-query-log on, so I can see the sql hitting MySQL.
And I noticed that Specifying a bigger limit in Django's QuerySet would not work:

>>> from blog.models import Author  
>>> len(Author.objects.filter(pk__gt=0)[0:999])
>>> len(Author.objects.all()[0:999])

And MySQL's general log showed that both query had LIMIT 21.

But a limit smaller than 21 would work, e.g. len(Author.objects.all()[0:10]) would make a sql with LIMIT 10.

Why is that? Is there something I need to configure?

Answer 1

It happens when you make queries from the shell - the LIMIT clause is added to stop your terminal filling up with thousands of records when debugging:

You were printing (or, at least, trying to print) the repr() of the queryset. To avoid people accidentally trying to retrieve and print a million results, we (well, I) changed that to only retrieve and print the first 20 results and print "remainder truncated" if there were more. This is achieved by limiting the query to 21 results (if there are 21 results there are more than 20, so we print the "truncated" message). That only happens in the repr() -- i.e. it's only for diagnostic printing. No normal user code has this limit included automatically, so you happily create a queryset that iterates over a million results.

(Source)