The postgres_fdw module is a foreign data wrapper (FDW) that you can use to access data stored in a remote PostgreSQL or Greenplum database.
Installing and Registering the Module
The postgres_fdw module is installed when you install Greenplum Database. Before you can use the foreign data wrapper, you must register the postgres_fdw extension in each database in which you want to use the foreign data wrapper.
Greenplum Database Limitations
When you use the foreign data wrapper to access Greenplum Database, postgres_fdw has the following limitations:
- The ctid is not guaranteed to uniquely identify
the physical location of a row within its table. For example, the
following statements may return incorrect results when the foreign
table references a Greenplum Database table:
INSERT INTO rem1(f2) VALUES ('test') RETURNING ctid; SELECT * FROM ft1, t1 WHERE t1.ctid = '(0,2)';
- postgres_fdw does not support local or remote triggers when you use it to access a foreign table that references a Greenplum Database table.
- UPDATE or DELETE operations on a foreign table that references a Greenplum table are not guaranteed to work correctly.
Additional Module Documentation
Refer to the postgres_fdw PostgreSQL documentation for detailed information about this module.