Federal Inquiry

Federated queries are to access external data sources through MatrixDB, including MySQL, PostgreSQL and other databases. The reading and writing process is like accessing the internal data table of MatrixDB.

Federal queries are implemented using Foreign Data Wrapper (FDW). FDW is a Postgres implementation developed by SQL standard SQL/MED (SQL Management of External Data). FDW provides a series of unified public interfaces, allowing extensions to easily integrate in-depth with Postgres in core parts such as optimization, execution, scanning, update and statistics, so that external data sources can be directly queried and operated with SQL statements. For example, FDW for MySQL, users can directly query, sort, group, filter, join, and even insert and update MySQL data like operating local tables. There are already many FDW extensions in the community, including commonly used databases, and access to local files, HDFS, etc.

This document will introduce readers to how to use FDW to access PostgreSQL, MySQL, MongoDB, and how to use PXF to access HDFS, Hive ORC, etc.