Document databases could support joins, and occasionally I wish MongoDB would handle them for me. All the plumbing's there, they just need a query engine that

Document databases could support joins, and occasionally I wish MongoDB would handle them for me. All the plumbing's there, they just need a query engine that can take advantage of it. The great thing about document databases is that you don't have to normalize them to keep your data structured, but you can normalize if it makes sense. When you normalize, joins become really handy.