How do I get the _count in my content provider?

What should I do to get my content provider to return the _count column with the count of records? The documentation says it is automatic, but maybe it's only taking about some built-in content provider. Running a query to the database seems not to return it.

From stackoverflow

• If you are using ContentProvider.query() a Cursor is returned. Call Cursor.getCount() to get a count of records in the returned cursor.