Question

I have not clearly issue during query using two criterials like Id and Other. I use a Repository storing some data like id,iso,value. I have created an index(“_id”,”Iso”) to performs queries but queries are only returning my cursor if i use only one criterial like _id, but is returning nothing if a use two (_id, Iso) (commented code).
Are the index affecting the response or the query method are failing?
use :v1.6.5 and C# official.

Sample.

//Getting Data
public List<BsonObject> Get_object(string ID, string Iso)
{
    using (var helper = BsonHelper.Create())
    {
        //helper.Db.Repository.EnsureIndex("_Id","Iso");
        var query = Query.EQ("_Id", ID);
        //if (!String.IsNullOrEmpty(Iso))
        //    query = Query.And(query, Query.EQ("Iso", Iso));
        var cursor = helper.Db.Repository.FindAs<BsonObject>(query);
        return cursor.ToList();
    }
}

Data:

{  
    "_id": "2345019",  
    "Iso": "UK",  
    "Data": "Some data"  
}

After that I have Updated my data using Update.Set() methods. I can see the changed data using MongoView. The new data are correct but the query is always returning the sames olds values. To see these values i use a page that can eventually cached, but if add a timestamp at end are not changing anything, page is always returning the same olds data. Your comments are welcome, thanks.

Answer 1

I do not recall offhand how the C# driver creates indexes, but the shell command for creating an index is like this:

db.things.ensureIndex({j:1});

Notice the ‘1’ which is like saying ‘true’.

In your code, you have:

helper.Db.Repository.EnsureIndex("_Id","Iso");

Perhaps it should be:

helper.Db.Repository.EnsureIndex("_Id", 1);
helper.Db.Repository.EnsureIndex("Iso", 1);

It could also be related to the fact that you are creating indexes on “_Id” and the actual id field is called “_id” … MongoDB is case sensitive.

Have a quick look through the index documentation: http://www.mongodb.org/display/DOCS/Indexes