title: postgresql return single row from function after select statement
body: <p>How can I return single row from postgresql function? What type should I use after <code>returns</code>?
  These is my code:</p>
  
  <pre><code>create or replace function get_perf()
  returns ???? as $$  
  select task_ext_perf.performance, task_ext_perf.unit from task_ext_perf order by task_ext_perf.tm limit 1; 
  $$
  language sql;
  </code></pre>