I am creating a plugin that adds two custom post types, one of which will always be a child of the other. The parent post type is for Events, the child for Performances. Before entering the Loop, I'd like to be able to find a set of Events that have Performances on a specific date. Performance date is stored as a meta field on the Performance post. The Loop would then list each Event matched, like in a standard post archive loop.
My preference is to query the Event post type, since that strikes me as easier to manage for pagination, but if there's a better implementation that simply involves querying performances, I am open to that, but I'd like to see if there's a facility for limiting a query based on a field in the child post.