Apache Calcite: A Foundational Framework for Optimized Query Processing Over Heterogeneous Data Sources Edmon Begoli Jesús Camacho-Rodríguez Julian Hyde Oak Ridge National Laboratory Hortonworks Inc. Hortonworks Inc. (ORNL) Santa Clara, California, USA Santa Clara, California, USA Oak Ridge, Tennessee, USA
[email protected] [email protected] [email protected] Michael J. Mior Daniel Lemire David R. Cheriton School of University of Quebec (TELUQ) Computer Science Montreal, Quebec, Canada University of Waterloo
[email protected] Waterloo, Ontario, Canada
[email protected] ABSTRACT argued that specialized engines can offer more cost-effective per- Apache Calcite is a foundational software framework that provides formance and that they would bring the end of the “one size fits query processing, optimization, and query language support to all” paradigm. Their vision seems today more relevant than ever. many popular open-source data processing systems such as Apache Indeed, many specialized open-source data systems have since be- Hive, Apache Storm, Apache Flink, Druid, and MapD. Calcite’s ar- come popular such as Storm [50] and Flink [16] (stream processing), chitecture consists of a modular and extensible query optimizer Elasticsearch [15] (text search), Apache Spark [47], Druid [14], etc. with hundreds of built-in optimization rules, a query processor As organizations have invested in data processing systems tai- capable of processing a variety of query languages, an adapter ar- lored towards their specific needs, two overarching problems have chitecture designed for extensibility, and support for heterogeneous arisen: data models and stores (relational, semi-structured, streaming, and • The developers of such specialized systems have encoun- geospatial). This flexible, embeddable, and extensible architecture tered related problems, such as query optimization [4, 25] is what makes Calcite an attractive choice for adoption in big- or the need to support query languages such as SQL and data frameworks.