[sql] Sleep function in ORACLE

I need execute an SQL query in ORACLE it takes a certain amount of time. So I wrote this function:

CREATE OR REPLACE FUNCTION MYSCHEMA.TEST_SLEEP
(
TIME_  IN  NUMBER
)
RETURN INTEGER IS
 BEGIN
   DBMS_LOCK.sleep(seconds => TIME_);
RETURN 1;
 EXCEPTION
   WHEN OTHERS THEN
   RAISE;
   RETURN 1;
END TEST_SLEEP;

and I call in this way

SELECT TEST_SLEEP(10.5) FROM DUAL

but to work I need set grant of DBMS_LOCK to the owner of the procedure.

How I can rewrite this function without using the DBMS_LOCK.sleep function?

What's about Java code wrapped by a procedure? Simple and works fine.

CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED SNOOZE AS
public final class Snooze {
  private Snooze() {
  }
  public static void snooze(Long milliseconds) throws InterruptedException {
      Thread.sleep(milliseconds);
  }
}

CREATE OR REPLACE PROCEDURE SNOOZE(p_Milliseconds IN NUMBER) AS
    LANGUAGE JAVA NAME 'Snooze.snooze(java.lang.Long)';

Create a procedure which just does your lock and install it into a different user, who is "trusted" with dbms_lock ( USERA ), grant USERA access to dbms_lock.

Then just grant USERB access to this function. They then wont need to be able to access DBMS_LOCK

( make sure you don't have usera and userb in your system before running this )

Connect as a user with grant privs for dbms_lock, and can create users

drop user usera cascade;
drop user userb cascade;
create user usera default tablespace users identified by abc123;
grant create session to usera;
grant resource to usera;
grant execute on dbms_lock to usera;

create user userb default tablespace users identified by abc123;
grant create session to userb;
grant resource to useb

connect usera/abc123;

create or replace function usera.f_sleep( in_time number ) return number is
begin
 dbms_lock.sleep(in_time);
 return 1;
end;
/

grant execute on usera.f_sleep to userb;

connect userb/abc123;

/* About to sleep as userb */
select usera.f_sleep(5) from dual;
/* Finished sleeping as userb */

/* Attempt to access dbms_lock as userb.. Should fail */

begin
  dbms_lock.sleep(5);
end;
/

/* Finished */

You can use DBMS_PIPE.SEND_MESSAGE with a message that is too large for the pipe, for example for a 5 second delay write XXX to a pipe that can only accept one byte using a 5 second timeout as below

dbms_pipe.pack_message('XXX');<br>
dummy:=dbms_pipe.send_message('TEST_PIPE', 5, 1);

But then that requires a grant for DBMS_PIPE so perhaps no better.

If executed within "sqlplus", you can execute a host operating system command "sleep" :

!sleep 1

or

host sleep 1

From Oracle 18c you could use DBMS_SESSION.SLEEP procedure:

This procedure suspends the session for a specified period of time.

DBMS_SESSION.SLEEP (seconds  IN NUMBER)

DBMS_SESSION.sleep is available to all sessions with no additional grants needed. Please note that DBMS_LOCK.sleep is deprecated.

If you need simple query sleep you could use WITH FUNCTION:

WITH FUNCTION my_sleep(i NUMBER)
RETURN NUMBER
BEGIN
    DBMS_SESSION.sleep(i);
    RETURN i;
END;
SELECT my_sleep(3) FROM dual;

It would be better to implement a synchronization mechanism. The easiest is to write a file after the first file is complete. So you have a sentinel file.

So the external programs looks for the sentinel file to exist. When it does it knows that it can safely use the data in the real file.

Another way to do this, which is similar to how some browsers do it when downloading files, is to have the file named base-name_part until the file is completely downloaded and then at the end rename the file to base-name. This way the external program can't "see" the file until it is complete. This way wouldn't require rewrite of the external program. Which might make it best for this situation.

Seems the java procedure/function could work. But why don't you compile your function under a user like the application schema or a admin account that has this grant and just grant your developer account execute on it. That way the definer rights are used.

You can use the DBMS_ALERT package as follows:

CREATE OR REPLACE FUNCTION sleep(seconds IN NUMBER) RETURN NUMBER
AS
    PRAGMA AUTONOMOUS_TRANSACTION;
    message VARCHAR2(200);
    status  INTEGER;
BEGIN
    DBMS_ALERT.WAITONE('noname', message, status, seconds);
    ROLLBACK;
    RETURN seconds;
END;

SELECT sleep(3) FROM dual;

There is a good article on this topic: PL/SQL: Sleep without using DBMS_LOCK that helped me out. I used Option 2 wrapped in a custom package. Proposed solutions are:

Option 1: APEX_UTIL.sleep

If APEX is installed you can use the procedure “PAUSE” from the publicly available package APEX_UTIL.

Example – “Wait 5 seconds”:

SET SERVEROUTPUT ON ;
BEGIN
    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    APEX_UTIL.PAUSE(5);
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
END;
/

Option 2: java.lang.Thread.sleep

An other option is the use of the method “sleep” from the Java class “Thread”, which you can easily use through providing a simple PL/SQL wrapper procedure:

Note: Please remember, that “Thread.sleep” uses milliseconds!

--- create ---
CREATE OR REPLACE PROCEDURE SLEEP (P_MILLI_SECONDS IN NUMBER) 
AS LANGUAGE JAVA NAME 'java.lang.Thread.sleep(long)';

--- use ---
SET SERVEROUTPUT ON ;
BEGIN
    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    SLEEP(5 * 1000);
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
END;
/

If Java is installed on your 11G then you can do it in a java class and call it from your PL/SQL, but I am not sure that it does not require also a specific grant to call java.