How does one add a partial index checking for NULL to a JSON column on Postgres? <p>I've got a <code>json</code> column called <code>data</code> on Postgres, and I'd like to add a partial index that applies only to rows where this column is <code>null</code> - I basically need to find all the rows where <code>data</code> is <code>null</code> so I can put some data into them. </p> <p>Trying to add an index gives an error about missing operator classes, though, because we can't index <code>json</code> types with a <code>btree</code> index. But I'm not trying to index a specific property either, for me to use <code>data-&gt;&gt;property</code>. How can I index just the rows which have a <code>json</code> null in them?</p> <p>Edit: The <code>jsonb</code> suggestion would work, but I'm stuck on 9.3 for this project.</p>