[databass]

Recursive CTEs are a cool feature, but it's a shame the syntax is so awful. You really have to work to understand what the query is trying to do.

Other query languages that make recursion much more bearable are SPARQL (on RDF data), Cypher (Neo4j) or Datalog (Datomic, Cascalog, etc). Would love to see more of those query languages being used.