Foreign data wrappers are objects used to consume data from different data sources not necessarily other PostgreSQL database system. These different data sources can be CSV files, web services or even database servers from different vendors.
||The name of a previously registered function that will be called to retrieve the execution functions for foreign tables. The handler function must take no arguments, and its return type must be
||The name of a previously registered function that will be called to check the generic options given to the foreign data wrapper, as well as options for foreign servers, user mappings and foreign tables using the foreign data wrapper.|
||Specifies the options for the foreign data wrapper. The allowed option names and values are specific to each foreign data wrapper and are validated using the foreign data wrapper's validator function.|
** Foreign data wrapper DDL **