title: Do I need to create separate index for primary key of relational database table
body: <p>If I create table with primary key is index automatically created for the table or does that need doing separately.</p>
  
  <p>i.e if this is the table ddl</p>
  
  <pre><code> CREATE TABLE release(guid varchar(36) NOT NULL PRIMARY KEY,
  name varchar(255),xmldata  CLOB(512 K))
  </code></pre>
  
  <p>do I also need to do </p>
  
  <pre><code>CREATE INDEX release_idx ON release(guid)
  </code></pre>
  
  <p>or not</p>
  
  <p>(I'm using Derby a database that comes with Java)</p>