If I only do one SELECT dblink_connect('{0}', '{1}'); SELECT dblink('{2}', '{3}'); SELECT dblink_disconnect('{4}'); where {3} is NOTIFY upd_pgm, '0|UPDATE|A|'; NOTIFY upd_pgm, '0|DELETE|A|'
only the notify with UPDATE is recognized.
"
dblink executes a query (usually a SELECT, but it can be any SQL statement that returns rows) in a remote database.
As defined in the dblink docs your query isn't supported - its doesn't return rows. I don't know the interaction that makes the separate executions succeed by I'd advise simply bypassing the issue and doing: