Apache Tajo is an open-source big data relational and distributed data warehouse system that provides fault-tolerant analytical processing on large-scale datasets. It is compatible with Apache Hadoop and HDFS and supports SQL standards including complex queries, joins, and aggregations. [05][06][01]

Apache Tajo is designed to be scalable and can process massive data sets with tens of thousands of nodes. It supports various file formats, including CSV, TSV, ORC, and Parquet. The Tajo constructs a master-slave cluster with master nodes and worker nodes. The master nodes manage the cluster and coordinate query execution, while the worker nodes perform the actual data processing.

Tajo also supports user-defined functions (UDFs), which allow users to extend the functionality of Tajo with their custom logic. Additionally, Tajo includes a web-based user interface and a command-line interface for managing and querying data. For optimizations, Tajo provides a cost-based optimization model and an expandable rewrite rule. A commercial solution with similar functionality is Cloudera's Impala.