A custom protocol allows you to connect Greenplum Database to a data source that cannot be accessed with the file://, gpfdist://, or pxf:// protocols.

Creating a custom protocol requires that you implement a set of C functions with specified interfaces, declare the functions in Greenplum Database, and then use the CREATE TRUSTED PROTOCOL command to enable the protocol in the database.

See Example Custom Data Access Protocol for an example.

Parent topic: Defining External Tables