HOW-TO Mongo Aggregration Framework.rst

Mongo Aggregration Framework

Operators

$project        reshapes a collection
$match          filter
$group          'group by' operator
$sort
$skip, $limit
$unwind         'explodes' array elements (1:n)
$out            writes out the cursor to a collection
$redact         security feature to screen what users can see
$geonear        location-aware operations