p = db.jstests_hint1; p.drop(); p.save( { ts: new Date( 1 ), cls: "entry", verticals: "alleyinsider", live: true } ); p.ensureIndex( { ts: 1 } ); e = p.find( { live: true, ts: { $lt: new Date( 1234119308272 ) }, cls: "entry", verticals: " alleyinsider" } ).sort( { ts: -1 } ).hint( { ts: 1 } ).explain(); assert.eq( e.indexBounds.ts[0][0].getTime(), new Date( 1234119308272 ).getTime() , "A" ); assert.eq( 0 , e.indexBounds.ts[0][1].getTime() , "B" );