The document discusses PostgreSQL's support for accessing remote data sources through SQL/MED. It describes how PostgreSQL has evolved from only supporting reads of remote data in early versions to supporting writes in version 9.3 by introducing foreign data wrappers. These wrappers allow PostgreSQL to access a variety of data sources like Oracle, MySQL, NoSQL databases, and file systems. The document envisions continued improvements to introspection of remote schemas and full compliance with the SQL/MED standard.