Obtaining latest versions, and similar aggregation patterns

We have seen this pattern in customer POCs and online:

Select all documents that are represent the latest revision for a user or some other key, or the latest arrival time, or some other aggregate. The solution pattern is:

• GROUP BY the keys
• wrap an aggregation function, e.g. MAX, MIN, around an array pair containing 2 items: the comparison expression and the document reference.

See this stack overflow for an example of both the question and the solution: http://stackoverflow.com/questions/34117559/obtaining-last-revisions-in-couchbase-with-n1ql/34122200#34122200