Executing External Programs From Within Oracle

Finally, Oracle 10g has given us the ability to execute
external programs from within Oracle. Let’s take a look at what we need to do
to expose this new feature.

DBMS_JOB

It must first be stated, or you might get
confused as I did, that the DBMS_JOB package that was widely used in earlier
versions of Oracle is now being left behind in Oracle 10g for the greater
capabilities of the DBMS_SCHEDULER package. This new package allows us to
manage jobs with greater versatility.

DBMS_SCHEDULER

This new job scheduler allows the database to handle a much
fuller set of scheduling and monitoring capabilities. The vast amount of
capabilities of the scheduler are beyond the scope of this article but I would encourage
you to explore the manuals and determine which of the features will fit in your
environment. I am confident you will switch from the old DBMS_JOBS to the new
DBMS_SCHEDULER. If there was one feature that will get you to switch
DBMS_SCHEDULER, it is its extended ability to handle a multitude of recurring
time intervals. In addition, with this new scheduler we have the ability to
control the execution of internal database applications as well as external
applications. The new DBMS_SCHEDULER has three distinct parts.

Create a Program

As stated above, the program is a definition of what
external program or application we will run. Listing 1 and Table 1 give you
examples of how to define an external program to execute and what the
parameters are used for. Listing 2 also gives you the external shell contents
that are being executed from this scheduled program. Within this shell, you can
execute anything that you would normally execute from within a shell script.

Listing 1.
Create a program to execute an external application

BEGIN

DBMS_SCHEDULER.CREATE_PROGRAM (

program_name            => ‘VMSTAT_PGM’,

program_type            => ‘EXECUTABLE’,

program_action          => ‘/home/oracle/vmstat.sh’,

enabled                 => TRUE,

comments                => ‘generate vmstat output’

);

END;

/

Table 1.

CREATE_PROGRAM
Parameters 

Listing 2.
The External Program

[oracle@bier oracle]$ cat vmstat.sh

/usr/bin/vmstat >> /tmp/vmstat.LST

Creat a Job

Now that we have a program to execute defined,
we must tell the database when to execute it. This is done by the creation of a
job. Listing 3 and Table 3 give you an example of how to create the job and the
parameters associated with the create statement.

Listing 3.

Creating a job to execute

BEGIN

DBMS_SCHEDULER.CREATE_JOB (

   job_name          =>  ‘VMSTAT_JOB’,

   program_name      =>  ‘VMSTAT_PGM’,

   repeat_interval   =>  ‘FREQ=SECONDLY;INTERVAL=5’,

   enabled            =>  TRUE,

   comments          =>  ‘Every 5 seconds’);

END;

/

Table 3.

CREATE_JOB
Parameters