title: "WHERE ... IN (...)" using pgx
body: <p>I am using postgresql go client: github.com/jackc/pgx
  I would like to execute SQL query looking a bit like this one:</p>
  
  <pre><code>ids := []int{2,3,4}
  rows, err = pool.Query("SELECT id, title FROM document WHERE id IN ($1)", ids)
  </code></pre>
  
  <p>The result is a following error: <code>cannot convert [2 3 4] to Int8</code></p>
  
  <p>Can I achieve such effect without concatenating string like <code>id=$1 OR id=$2 OR....</code> ?</p>