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Under the hood of Oracle's file watchers

A file watcher is triggered by an (ordinary) schedule, named FILE_WATCHER_SCHEDULE.

By default, the schedule runs every ten minutes:

select
   sch.schedule_type,
   sch.repeat_interval
from
   dba_scheduler_schedules sch
where
   sch.owner         = 'SYS'                   and
   sch.schedule_name = 'FILE_WATCHER_SCHEDULE';
--
-- SCHEDULE_TYPE        REPEAT_INTERVAL
-- -------------------- ------------------------------
-- CALENDAR             FREQ=MINUTELY;INTERVAL=10

The schedule starts a job named FILE_WATCHER which is associated with a program named FILE_WATCHER_PROGRAM:

select
   job.job_name,
   job.program_name,
   job.job_class,
   job.comments
-- job.last_start_date
from
   dba_scheduler_jobs job
where
   job.schedule_name = 'FILE_WATCHER_SCHEDULE';
--
-- JOB_NAME      PROGRAM_NAME          JOB_CLASS                   COMMENTS         
-- ------------- --------------------- --------------------------- -----------------
-- FILE_WATCHER  FILE_WATCHER_PROGRAM  SCHED$_LOG_ON_ERRORS_CLASS  File watcher job

This program (FILE_WATCHER_PROGRAM) corresponds to the PL/SQL procedure dbms_ischedfw.file_watch_job:

select
   prg.program_type,
   prg.program_action,
   prg.number_of_arguments args,
   prg.comments
from
   dba_scheduler_programs prg
where
   prg.owner = 'SYS' and
   prg.program_name = 'FILE_WATCHER_PROGRAM';
--
-- PROGRAM_TYPE       PROGRAM_ACTION                     ARGS COMMENTS             
-- ------------------ ---------------------------- ---------- ---------------------
-- STORED_PROCEDURE   dbms_ischedfw.file_watch_job          0 File Watcher program

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