DIQL is a query language for Apache Spark that is deeply embedded in Scala. The DIQL compiler optimizes DIQL queries and translates them to Java byte code at compile-time. DIQL can uniformly work on any collection that conforms to the Scala classes RDD or Traversable, thus allowing one to query both distributed and in-memory collections using the same syntax. DIQL queries may use any Scala pattern, may access any Scala variable, and may embed any Scala code, including calls to RDD methods.