Graph Lookup in MongoDB 3.3

Specialized graph databases such as Neo4J specialize in traversing graphs of relationships – such as those you might find in a social network.  Many non-graph databases have been incorporating Graph Compute Engines to perform similar tasks.  In the MongoDB 3.3 release, we now have the ability to perform simple graph traversal using the $graphLookup aggregation framework function.  This will become a production feature in the 3.4 release.

The new feature is documented in MongoDB Jira SERVER-23725.  The basic syntax is shown here:

   1: {$graphLookup:

   2:         from: <name of collection to look up into>,

   3:         startWith: <expression>,

   4:         connectFromField: <name of field in document from “from”>,

   5:         connectToField: <name of field in document from “from”>,

   6:         as: <name of field in output document>,

   7:         maxDepth: <optional - non-negative integer>,

   8:         depthField: <optional - name of field in output

   9:  documents>

  10:     }

Please go to https://medium.com/dbkoda/optimising-graph-lookups-in-mongodb-49483afb55c8 to read the rest of this article (updated for MongoDB 3.6)