Autonomous DB "You have exceeded the maximum number of web service requests per workspace"

We recently had an experience on an Oracle Autonomous Database where our production instance started giving us lots of errors saying:

ORA-20001: You have exceeded the maximum number of web service requests per workspace. Please contact your administrator.

After some investigation, I found a couple of interesting blog posts by Dimitri Gielis and Scott Wesley that seemed to address this exact issue.

https://dgielis.blogspot.com/2018/09/increasing-maximum-web-service-requests.html

http://www.grassroots-oracle.com/2019/03/oracle-apex-web-service-request-limit.html

As these two blog posts tell us, in a self-managed or in-house APEX installation, the page for changing the Maximum Web Service Requests parameter can be found under "Security settings -> Workspace Isolation -> Maximum Web Service Requests".  We can increase the parameter there and fix the issue.

However, on the Autonomous DB these pages are not available.  So the questions become: Can we change this parameter? and if so, how and where?

A further flurry of Googling and a deeper dive into the Oracle Documentation led us to the following page: https://docs.oracle.com/en/cloud/paas/autonomous-database/adbsa/apex-web-services.html#GUID-DA24C605-384D-4448-B73C-D00C02F5060E

Here we see that there is an APEX instance-level parameter called MAX_WEBSERVICE_REQUESTS which can be queried and modified using the APEX_INSTANCE_ADMIN package.  The default value of this parameter on an Autonomous DB is currently 50'000 outgoing requests in a rolling 24-hour period.  To run this package you must be connected as the ADMIN user. 

To view the current value of MAX_WEBSERVICE_REQUESTS, we can execute the following query that uses the get_parameter function.  

select apex_instance_admin.get_parameter

          ('MAX_WEBSERVICE_REQUESTS') as requests

  from dual;

REQUESTS

--------

50000

To change this value, we can use the SET_PARAMETER procedure:

begin

 apex_instance_admin.set_parameter

     ('MAX_WEBSERVICE_REQUESTS', '250000');  -- increase to 250'000

 commit;

end;

/

If we rerun the preceding query again, we now get a different result that confirms that our change has worked.

select apex_instance_admin.get_parameter

          ('MAX_WEBSERVICE_REQUESTS') as requests

  from dual;

REQUESTS

--------

250000

I hope that this blog post helps someone out there avoid the minor panic that we experienced for a short while today.

Happy APEXing to all!