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
26964	No mention of index_together on the GenericForeignKey section	Aidan Lister	nobody	"We've been troubleshooting a performance issue and noticed that there was no index on an important GenericForiegnKey.

Once we'd resolved that, we noticed a contrib app had no index either (django reversion).

It seems like this should be mentioned in the documentation here:

https://docs.djangoproject.com/en/1.9/ref/contrib/contenttypes/#generic-relations

Suggested wording:

If you plan to search for child objects which have a generic relation to your parent object, e.g. find all tags linked to a piece of content, then you should consider adding a database index on the content type and object ID using index_together (https://docs.djangoproject.com/en/1.9/ref/models/options/#index-together). Django does not do this for you automatically as it does with ForeignKey's.

In the example above, this would look like:

```
    class Meta:
        index_together = [
            [""content_type"", ""object_id""],
        ]
```"	Bug	new	Documentation	1.9	Normal				Unreviewed	0	0	0	0	1	0