pg_cancelrequest
Name
pg_cancelrequest -- request that 
PostgreSQL 
  abandon processing of the current command
 
Synopsis
pg_cancelrequest conn
Description
   pg_cancelrequest requests that the processing
   of the current command be abandoned.
  
Arguments
- conn
-       The handle of a connection to the database in which the large object
      exists.
      
Return Value
   Returns nothing if the command was successfully dispatched or if no
   query was being processed.  Otherwise, returns an error.