title: Count file size in PostgreSQL
body: <p>I have this simple table which I would like to use to store files. </p>
  
  <pre><code>CREATE TABLE table(
   ID INTEGER NOT NULL,
   FILE_NAME TEXT,
   FILE OID
  )
  ;
  </code></pre>
  
  <p>Is there any way with SQL query to count the total size of the files into the table? Is this possible without function?</p>