title: PostgreSQL : function set_config(unknown, bigint, boolean) doesn't exist
body: <p>I am trying to use the current_setting() and set_config() functions for plpgpsq, to change the value of a custom setting I've added to my postgresql.conf file.</p>
  <p>Here's what I added to the end of my postgresql.conf file :</p>
  <pre><code>IntegrityPackage.NestLevel = 0
  </code></pre>
  <p>After restarting the PostgreSQL service, here's what I get when I want to see the setting's value :</p>
  <pre><code>select current_setting('IntegrityPackage.NestLevel');
  
  current_setting |
  ----------------|
  0               |
  </code></pre>
  <p>However, when I try to edit the value, I get an error message :</p>
  <pre><code>select set_config('IntegrityPackage.NestLevel', 0, false);
  
  ERROR: function set_config(unknown, bigint, boolean) doesn't exist.
  Hint: No function corresponds to given name and argument types
  You must add explicit type conversions
  </code></pre>
  <p>(Vaguely translated from french since the error message was in french)</p>
  <p>There is very little documnetation about this, therefore I'm stuck and I can't think of another way to do this.</p>
  <p><em>Edit</em> - the exact error text (in psql 9.2 / postgresql 10.0) is:</p>
  <pre><code>ERROR:  function set_config(unknown, integer, boolean) does not exist
  LINE 1: select set_config('my.foo',obj_id::int ,false) from objects ...
                 ^
  HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
  </code></pre>