title: How to use Postgresql GIN index with ARRAY keyword
body: <p>I'd like to create <code>GIN</code> index on a scalar text column using an <code>ARRAY[]</code> expression like so:</p>
  <pre><code>CREATE TABLE mytab (
   scalar_column TEXT
  )
  
  CREATE INDEX idx_gin ON mytab USING GIN(ARRAY[scalar_column]);
  </code></pre>
  <p>Postgres reports an error on <code>ARRAY</code> keyword.</p>
  <p>I'll use this index later in a query like so:</p>
  <pre><code>SELECT * FROM mytab WHERE ARRAY[scalar_column] &lt;@ ARRAY['some', 'other', 'values'];
  </code></pre>
  <p>How do I create such an index?</p>