Explain DBMS_UTILITY.FORMAT_ERROR_BACKTRACE and the error stack functions

In a handler, SQLERRM (or DBMS_UTILITY.FORMAT_ERROR_STACK) gives the error message, but not where it came from. DBMS_UTILITY.FORMAT_ERROR_BACKTRACE returns the call stack from the raise point to the current handler, including line numbers — essential when WHEN OTHERS is several calls away. Since 12c, UTL_CALL_STACK offers the same information in a structured, per-frame API. Log the backtrace before re-raising; do not let it be lost.

CREATE OR REPLACE PROCEDURE run_job AS
BEGIN
  -- ... deep call chain ...
  RAISE_APPLICATION_ERROR(-20500, 'step failed');
EXCEPTION
  WHEN OTHERS THEN
    INSERT INTO job_errors(err_msg, err_stack, logged_at)
    VALUES (SQLERRM,
            DBMS_UTILITY.FORMAT_ERROR_BACKTRACE,
            SYSTIMESTAMP);
    RAISE;                       -- keep propagating after logging
END;
/