This topic was originally presented by Lambert Lum at the SVPerl meeting on Feb 2, 2012. This wiki page contains links and notes about NoSQL databases and accessing them from Perl.
Summary and categorization of NoSQL databases: Visual Guide to NoSQL Systems by Nathan Hurst
MongoDB is the best developed of the NoSQL databases. There's a MongoDB Perl module.
UnQL - Unstructured Query Lanquage specification
-- IanKluft - 2012-02-02