Cancel a backend's current query.
Syntax:
procedure CancelBackend(PID : Integer);
Description:
Call CancelBackend to terminate backend's current query identified by process ID. The process ID of an active backend can be found from the procpid column of the pg_stat_activity view, or by listing the postgres processes on the server (using ps on Unix or the Task Manager on Windows).
Obviously this method should be executed from separate thread using separate TPSQLDatabase connection.