title: Postgres lock_timeout when CREATE UNIQUE INDEX CONCURRENTLY
body: <p>Having trouble creating unique index on a table. Statement fails with following message</p>
  
  <pre><code>&gt;CREATE UNIQUE INDEX CONCURRENTLY my_table_pkey_new ON my_table (new_id);
  ERROR:  canceling statement due to lock timeout
  </code></pre>
  
  <p>It is not clear why I get lock timeout. Concurrent index creation shouldn't lock the table.</p>
  
  <p>I also tried to increase lock timeout but without success</p>
  
  <pre><code>test=&gt; show lock_timeout;
   lock_timeout
  --------------
   5min
  (1 row)
  
  test=&gt; set lock_timeout to 99999999;
  SET
  test=&gt; show lock_timeout;
   lock_timeout
  --------------
   5min
  (1 row)
  </code></pre>