title: What is to_regclass argument data type in version 9.6?
body: <p>I use this piece for check  table existing in   version <code>9.5</code> and it   works fine:</p>
  
  <pre><code>do $$
  declare v text;
  begin
      SELECT to_regclass(('some'||'table')::cstring) into v;
      raise notice '%', v;
  end;
  $$ language plpgsql
  </code></pre>
  
  <p>Now I work with another (remote) database with version <code>9.6</code> and this code yields   error:</p>
  
  <blockquote>
    <p>function to_regclass(cstring) does not exist </p>
  </blockquote>
  
  <p>So, what is argument data type for <code>to_regclass()</code> function in postgres 9.6 ?</p>