Given your use case it would probably be ok to duplicate a little bit of data and store some of the necessary fields about the sending user as an embedded document - in this case, the username.
array (
'_id' => new MongoId("524358102660b2c70b8b4567"),
'from_user' => array(
'uid' => '5231817277758e660c7202d7',
'uname' => 'mars'
),
'to_uid' => '5231817277758e660c7202c4',
'object' => 'mongo manual Ref',
'content' => 'is that the correct approach?',
'datetime' => '2013-09-25 23:39:28',
)
This approach means that when you query for messages to a user ( in which you already know the to_uid
), you get all of the messages with the correct id to the from_user
, but also already have their username to display.
Now, instead of querying 1000+ times, you only need to query when there is more information needed about a user - such as fetching their profile, etc...