As Ozgun notes above, the Foreign Data Wrapper APIs just provide a powerful abstraction for what this extension is doing.
Though the DDL to set up a foreign table requires first creating a "server" with CREATE SERVER, this is merely a formality: as in file_fdw the server doesn't actually represent an external process. All I/O occurs within the postgres backend process servicing the query.
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(I'm Jason from Citus Data)
As Ozgun notes above, the Foreign Data Wrapper APIs just provide a powerful abstraction for what this extension is doing.
Though the DDL to set up a foreign table requires first creating a "server" with CREATE SERVER, this is merely a formality: as in file_fdw the server doesn't actually represent an external process. All I/O occurs within the postgres backend process servicing the query.