Nested Query

Searches over nested documents using ToParentBlockJoinQuery in Lucene.

Proto definition:

message NestedQuery {
    enum ScoreMode {
        NONE = 0;
        AVG = 1;
        MAX = 2;
        MIN = 3;
        SUM = 4;
    }
    Query query = 1; // query for the child documents
    string path = 2; // field name of the nested
    ScoreMode scoreMode = 3; // how child documents score affects final score
}