documentation for QuerySet.exists() a bit misleading?

[knewB]

​https://docs.djangoproject.com/en/1.4/ref/models/querysets/#exists
says "calling QuerySet.exists() is faster than bool(some_query_set), but not by a large degree."

Using SQLite and MySQL, QuerySet.exists() results in

SELECT (1) AS "a" FROM foo WHERE bar LIMIT 1

rather than

SELECT EXISTS(...) 

but in any case, isn't this a lot faster than bool(some_query_set) ?

[Luke Plant]

How much faster it is will depend on various factors (including how many rows there are in the DB that match the query, and also how the DB backend chunks results), and so it is not necessarily a lot faster.

As for the other thing you mentioned, you haven't shown a bug. If you can show that using EXISTS produces a significant performance gain, please detail your results and re-open.