$doc = [
'tags' => [
[ 'k' => 'name', 'v' => 'A440' ],
[ 'k' => 'highway', 'v' => 'secondary' ],
[ 'k' => 'oneway', 'v' => 'yes' ]
]
];
$db->poi->createIndex( [ 'tags.v' => 1, 'tags.k' => 1 ] );
// Road with name=Strand
$db->poi->find( [
'tags' => [ '$elemMatch' => [ 'k' : 'name', 'v' : 'Strand' ] ]
] );
// All roads
$db->poi->find( [ 'tags.k' => 'highway' ] );