dblink is a module that supports connections to other PostgreSQL databases from within a database session.
dblink can report the following wait events under the wait event type Extension.
DblinkConnectWaiting to establish a connection to a remote server.
DblinkGetConnectWaiting to establish a connection to a remote server when it could not be found in the list of already-opened connections.
DblinkGetResultWaiting to receive the results of a query from a remote server.
See also postgres_fdw, which provides roughly the same functionality using a more modern and standards-compliant infrastructure.
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