asterix-installer/src/main/resources/examples/mugshot/aql/left-outer-join-aggr.aql

use dataverse TinySocial;

for $user in dataset MugshotUsers
let $result := {
    "uname" : $user.name,
    "msg-length" : avg(
        for $message in dataset MugshotMessages
        where $message.author-id = $user.id
        return string-length($message.message)
      )
  }
order by $result.msg-length desc
limit 10
return $result;