PostgreSQL provides a way to communicate with external data sources. This could be another PostgreSQL instance or any other database. The other database might be a relational database, such as MySQL or Oracle; or any NoSQL database such as MongoDB or Hadoop. To achieve this, PostgreSQL implements ISO Standard call SQL-MED in the form of Foreign Data Wrappers (FDW). This presentation will explain in detail how PostgreSQL FDWs work. It will include a detailed explanation of simple features and will introduce more advanced features that were added in recent versions of PostgreSQL. Examples of these would be to show how aggregate pushdown and join pushdown work in PostgreSQL.
The talk will include working examples of these advanced features and demonstrating their use with different databases. These examples show how data from different database flavors can be used by PostgreSQL, including those from heterogeneous relational databases, and showing NoSQL column store joins.