The useDFE SPARQL query hint - Amazon Neptune

The useDFE SPARQL query hint

Use this query hint to enable use of the DFE for executing the query. By default Neptune does not use the DFE without this query hint being set to true, because the neptune_dfe_query_engine instance parameter defaults to viaQueryHint. If you set that instance parameter to enabled, the DFE engine is used for all queries except those having the useDFE query hint set to false.

Example of enabling use of the DFE for a query:

PREFIX : <https://example.com/>
PREFIX hint: <http://aws.amazon.com/neptune/vocab/v01/QueryHints#>

SELECT ?john ?jane
{
  hint:Query hint:useDFE true .
  ?person1 :name "Jane" .
  ?person1 :likes ?person2 .
  ?person2 :name "John" .
  ?person2 :likes ?person1 .
}