title: Product Aggregate in PostgreSQL
body: <p>I try to create an aggregate for product (*) in PostgreSQL.
  The field type of my row is "double precision"</p>
  
  <p>So, I tried :</p>
  
  <pre><code>CREATE AGGREGATE nmul(numeric)
  (
     sfunc = numeric_mul,
     stype = numeric
  );
  </code></pre>
  
  <p>When I launch my query, the result :</p>
  
  <pre><code>ERROR:  function nmul(double precision) does not exist
  LINE 4: CAST(nmul("cote") AS INT),
  </code></pre>
  
  <p>Thank you</p>