id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
24296	clear select fields for `.exists()` of distinct, non-sliced querysets	Martin Chase	Marcelo Galigniana	"The fix (93cc6dcdac6fc3e506640fa38dd1798c3cd61cff) for bug #18414 introduced an inefficiency in `.exists()` on distinct querysets in that now all distinct querysets are selecting all their fields. I propose the fields should be left on the queryset only if `(q.distinct and (q.high_mark is not None or q.low_mark is not None))`.

As I started writing the test for this, I realized I would have to inspect the query itself, which seems... like a bad idea for a test. Would this be reasonable to submit the (one-line-change) patch without a test, or does someone have a suggestion for a way to make the test that's less brittle?"	Cleanup/optimization	closed	Database layer (models, ORM)	1.7	Normal	fixed			Ready for checkin	1	0	0	0	0	0