—We demonstrate SWITCH, a deep embedding of relational queries into RUBY and RUBY on RAILS. With SWITCH, there is no syntactic or stylistic difference between RUBY programs that operate over in-memory array objects or databaseresident tables, even if these programs rely on array order or nesting. SWITCH’s built-in compiler and SQL code generator guarantee to emit few queries, addressing long-standing performance problems that trace back to RAILS’ ACTIVERECORD database binding. “Looks likes RUBY, but performs like handcrafted SQL,” is the ideal that drives the research and development effort behind SWITCH. I. RUBY ON RUTTED RAILS RUBY on RAILS (or RAILS, for short) is found among the most actively deployed frameworks that support the rapid development of Web 2.0–style applications [11]. Notable RAILS applications abound, with GitHub, Qype, Twitter, or Xing being only a few of those widely recognized on the Web. A RAILS–built application follows a strict model–view– con...