Foreign Data Wrappers (FDW)

Foreign Data Wrappers (FDW) are PostgreSQL's implementation of the SQL/MED standard defined by ISO/IEC 9075-9:2003. PostgreSQL is the first (and so far only) mainstream RDBMS to provide this capability, which was initially added in release 9.1 and has been extended continually ever since.


Foreign data wrappers are available for many other databases and datastores, as well as a variety of alternative data sources including flat files, web APIs etc. See this matrix for an overview of FDWs available for other SQL databases.


Timeline of SQL/MED implementation in PostgreSQL:



Articles and blog posts about foreign data wrappers

Global sequences with postgres_fdw and Postgres core
Sharing sequences across multiple PostgreSQL instances (Michael Paquier)
Generating Create Foreign Table Statements for postgres_fdw
PostGIS-orientated but interesting approach (Leo Hsu/Regina Obe)
Foreign Data Wrappers for PostgreSQL 9.4 Windows
file_textarray_fdw, www_fdw and ogr_fdw packaged for Windows (Leo Hsu/Regina Obe)