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
29317	filter keyword undocumented in PostgreSQL aggregate functions	Matthew Pava	Scott Halgrim	"The signature for all of the aggregate functions for PostgreSQL includes a `filter` keyword argument, but I can't figure out what it is used for based on the documentation alone: [https://docs.djangoproject.com/en/2.0/ref/contrib/postgres/aggregates/].

For what it's worth, I'm trying to filter out all of the empty values in an `ArrayAgg` expression, which seems to be a fairly common thing that one would want to do.  Perhaps we could add an example to the documentation showing how that can be accomplished.  I'm not sure right now if the `filter` keyword argument is the way to go."	Cleanup/optimization	closed	Documentation		Normal	fixed	aggregate	Tom Forbes	Accepted	0	0	0	0	0	0