Apache Calcite
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| Apache Calcite | |
|---|---|
| Name | Apache Calcite |
| Developer | Apache Software Foundation |
| Released | 2014 |
| Programming language | Java |
| License | Apache License 2.0 |
Apache Calcite is an open-source dynamic data management framework providing SQL parsing, query optimization, and query execution planning for heterogeneous data systems. It acts as a metadata-driven query planner and optimizer used as a foundation by numerous projects across commercial vendors and research institutions, integrating with engines and storage systems to enable federated query processing and adaptive optimization.
Overview
Calcite originated to supply a modular, extensible optimizer and adapter layer between query frontends and execution backends, aligning with the needs of projects such as Apache Hive, Apache Drill, Apache Flink, Apache Spark, and Apache Beam. It emphasizes a relational algebra core, rule-based and cost-based optimization, and a flexible adapter model so systems like Dremio and Google BigQuery-style services can reuse its planner. Contributors include engineers from organizations like Twitter, Facebook, Cloudera, Oracle Corporation, Microsoft, and Netflix.
Architecture
Calcite's architecture separates parsing, validation, planning, and adapter layers, enabling integration with systems such as Kafka, HBase, Cassandra, Elasticsearch, and Snowflake. The core components consist of a SQL parser influenced by Apache Derby's grammar, a validator that resolves identifiers against schemas and catalogs like those used in PostgreSQL and MySQL, and a planner based on the Volcano and Cascades frameworks originally developed in academic projects at institutions like University of Wisconsin–Madison and University of California, Berkeley. Its schema and type system model metadata similar to Apache Avro and Protocol Buffers, and its adapter APIs permit connectors to storage systems including Amazon S3, Google Cloud Storage, and Azure Blob Storage.
Query Processing and Optimization
Calcite ingests SQL and relational expressions, leveraging rule-based transformations and a cost-based optimizer influenced by System R research from IBM Research and the Cascades framework originating with research groups at University of Wisconsin–Madison and Yale University. It implements a planner that applies transformation rules for join ordering (benefiting systems like Vertica and Teradata), predicate pushdown (used by Presto and Trino), projection pruning (seen in Greenplum), and aggregate rewriter rules used in OLAP systems such as ClickHouse and ClickHouse Inc.. Calcite supports materialized view rewriting as practiced in Oracle Database and Microsoft SQL Server, and supports cost models pluggable for engines including Apache Flink and Apache Spark SQL. It also supports rule sets for conversion to execution conventions for platforms like GraalVM-based runtimes and vectorized engines in Intel architectures.
Integrations and Connectors
Calcite provides adapter patterns and planner conventions to integrate with query engines and storage systems; notable integrations include Apache Hive, Apache Drill, Apache Flink, Apache Spark, Dremio, Presto, and Trino. Connectors and adapters enable federated queries across sources like MongoDB, Cassandra, HBase, Elasticsearch, BigQuery, and object stores such as Amazon S3 and Google Cloud Storage. It also underpins SQL layers in commercial systems from Cloudera, Palantir, Starburst Data, and Confluent where adapters translate Calcite plans into execution graphs for stream processors like Apache Kafka Streams and Flink SQL.
Use Cases and Deployments
Calcite is used in data warehousing, OLAP, ETL, and streaming analytics in products and projects such as Apache Hive, Apache Flink SQL, Apache Beam, Dremio, Starburst Enterprise, and proprietary offerings by Google, Microsoft Azure, and Amazon Web Services partners. It is employed to enable federated querying across heterogeneous backends in enterprise architectures involving Snowflake, BigQuery, and Redshift-style storage, to implement extensible SQL dialects for analytics platforms like Tableau integrations, and to power metadata-driven optimizers in research projects from institutions such as MIT, Stanford University, and ETH Zurich.
Development, Community, and Governance
Calcite is an Apache Software Foundation project governed by the Apache Software Foundation's meritocratic community model, with a Project Management Committee and contributors from companies like Google, Oracle Corporation, Microsoft, Facebook, Twitter, Cloudera, and Netflix. Development discussions occur on mailing lists and issue trackers commonly used in ASF projects, and releases adhere to ASF release processes similar to projects like Apache Hadoop and Apache Kafka. The project participates in community events such as ApacheCon and collaborates with academic researchers from Carnegie Mellon University and University of California, Berkeley on query optimization research.