Failure in Multi Map Index with Spatial Index in RavenDB - mapreduce

Question

I want to search for things that belong to users (near me). I have the following index defined, but I am not getting a merged resultset:
public class Things_ByLocation : AbstractMultiMapIndexCreationTask<Things_ByLocation.ThingsByLocationResult>
{
public class ThingsByLocationResult
{
public string ThingId { get; set; }
public string UserId { get; set; }
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public Things_ByLocation()
{
AddMap<Thing>(things => from t in things
select new
{
ThingId = t.Id,
UserId = (string)null,
Latitude = 0,
Longitude = 0,
_ = (object)null,
});
AddMap<User>(users => from u in users
select new
{
ThingId = (string)null,
UserId = u.Id,
Latitude = u.Latitude,
Longitude = u.Longitude,
_ = SpatialIndex.Generate(u.Latitude, u.Longitude)
});
Reduce = results => from result in results
group result by result.ThingId into g
let userId = g.Select(x => x.UserId).Where(t => !string.IsNullOrWhiteSpace(t)).FirstOrDefault()
let lat = g.Select(x => x.Latitude).Where(t => t != 0).FirstOrDefault()
let lng = g.Select(x => x.Longitude).Where(t => t != 0).FirstOrDefault()
select new
{
ThingId = g.Key,
UserId = userId,
Latitude = lat,
Longitude = lng,
_ = SpatialIndex.Generate(lat, lng)
};
Store(x => x.ThingId, FieldStorage.Yes);
Store(x => x.UserId, FieldStorage.Yes);
}
}
Result looks like this:
{
"ThingId": "Thing/Id26",
"UserId": null,
"Longitude": "0",
"__spatialShape": "0.000000 0.000000"
}
My models:
public class User
{
public string Id { get; set; }
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public class Thing
{
public string Id { get; set; }
public double Name { get; set; }
public double Description { get; set; }
public string UserId { get; set; }
}
Any ideas as to what I am doing wrong? If I switch the group to the user, the user section gets populated and the ThingId is null. Hence, it appears that the merging process is failing. I'm just not sure why.
It is also very odd, as to why the result show the Longitude, but not the Latitude property.
Working with RavenDB Build 960 in RAM.
I realise I could denormalize the location into the Thing, but that would mean that if the user location changed I would have to update potentially hundreds of Things. Is that the preferred NoSql way to do this?
UPDATE
Based on Ayende's suggestion I now have the following:
public class Things_ByLocation : AbstractMultiMapIndexCreationTask<Things_ByLocation.ThingsByLocationResult>
{
public class ThingsByLocationResult
{
public string ThingId { get; set; }
public string UserId { get; set; }
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public Things_ByLocation()
{
AddMap<Thing>(things => from t in things
select new
{
ThingId = t.Id,
UserId = (string)null,
Latitude = 0,
Longitude = 0
});
AddMap<User>(users => from u in users
select new
{
ThingId = (string)null,
UserId = u.Id,
Latitude = u.Latitude,
Longitude = u.Longitude
});
Reduce = results => from result in results
group result by result.ThingId into g
select new
{
ThingId = g.Key,
UserId = g.Select(x => x.UserId).Where(x => x != null).FirstOrDefault(),
Latitude = g.Select(x => x.Latitude).Where(t => t != 0).FirstOrDefault(),
Longitude = g.Select(x => x.Longitude).Where(t => t != 0).FirstOrDefault()
};
Store(x => x.ThingId, FieldStorage.Yes);
Store(x => x.UserId, FieldStorage.Yes);
}
}
The index itself:
Map:
docs.Things
.Select(t => new {ThingId = t.__document_id, UserId = (String)null, Latitude = 0, Longitude = 0})
Map:
docs.Users
.Select(u => new {ThingId = (String)null, UserId = u.__document_id, Latitude = ((double)u.Latitude), Longitude = ((double)u.Longitude)})
Reduce:
results
.GroupBy(result => result.ThingId)
.Select(g => new {ThingId = g.Key, UserId = g
.Select(x => x.UserId)
.Where(x => x != null).FirstOrDefault(), Latitude = g
.Select(x => ((double)x.Latitude))
.Where(t => t != 0).FirstOrDefault(), Longitude = g
.Select(x => ((double)x.Longitude))
.Where(t => t != 0).FirstOrDefault()})
The resulting projection looks like this:
{
"ThingId": "Thing/Id26",
"UserId": null,
"Latitude": null,
"Longitude": null
}
I appear to be doing something academically wrong here.

Answer 1

Try:
Removing SpatialIndex.Generate from the map, it should only be on the reduce.
Removing SpatialIndex.Generate from the reduce and just seeing why you don't the Latitude & Longitude as you should.

Answer 2

Through a process of trial and error (and Ayende's suggestion), I ended up with the following. It works works, but I have no idea why!
I have a suspicion that I would be best changing the data model and denormalize the geo location data into the Thing.
public class Things_ByLocation : AbstractMultiMapIndexCreationTask<Things_ByLocation.ThingsByLocationResult>
{
public class ThingsByLocationResult
{
public string Id { get; set; }
public string UserId { get; set; }
public double Latitude { get; set; }
public double Longitude { get; set; }
public string SKU { get; set; }
public string Name { get; set; }
}
public Things_ByLocation()
{
AddMap<Thing>(things => from t in things
select new
{
Id = t.Id,
UserId = t.UserId,
Latitude = 0,
Longitude = 0,
Name = t.Name,
SKU = t.SKU,
_ = (object)null,
});
AddMap<User>(users => from u in users
select new
{
Id = (string)null,
UserId = u.Id,
Latitude = u.Latitude,
Longitude = u.Longitude,
Name = (string)null,
SKU = (string)null,
_ = (object)null,
});
Reduce = results => from result in results
group result by result.Id into g
let lat = g.Select(x => x.Latitude).Where(x => x != 0).FirstOrDefault()
let lng = g.Select(x => x.Longitude).Where(x => x != 0).FirstOrDefault()
let userId = g.Select(x => x.UserId).Where(x => x != null).FirstOrDefault()
let name = g.Select(x => x.Name).Where(x => x != null).FirstOrDefault()
let sku = g.Select(x => x.SKU).Where(x => x != null).FirstOrDefault()
select new
{
Id = g.Key,
UserId = userId,
Latitude = lat,
Longitude = lng,
Name = name,
SKU = sku,
_ = SpatialIndex.Generate(lat, lng)
};
Store(x => x.Id, FieldStorage.Yes);
Store(x => x.UserId, FieldStorage.Yes);
TransformResults = (database, results) => from result in results
let user = database.Load<User>(result.UserId)
select new
{
Id = result.Id,
UserId = result.UserId,
Latitude = user.Latitude,
Longitude = user.Longitude,
Name = result.Name,
SKU = result.SKU,
};
}
}