Now Amazon DocumentDB supports new features for aggregations, arrays, and indexing

Amazon DocumentDB (with MongoDB compatibility) is a speedy, scalable, mostly accessible, and completely organized document database service which helps MongoDB workloads. Now, Amazon DocumentDB further assists for latest aggregation string operators ($concat, $substr, $substrBytes, $substrCP, $strcasecmp), an array aggregation operator ($size), an aggregation group accumulator operator ($push), and aggregation stages ($redact and $indexStats) which enables you to create strong aggregations over your documents. Besides, Amazon DocumentDB assists positional array operators ($[] and [<identifier>]) for updating elements in an array and hint() for selecting an index. You can produce a new Amazon DocumentDB cluster with couple of clicks in the Amazon DocumentDB Management Console or you can upgrade your current cluster to utilize this features. To know about this feature, read AWS Database Blog: New Amazon DocumentDB feature for aggregations, array, and indexing