RavenDB index with map reduce distinct [closed] - mapreduce

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Closed 9 years ago.
I have a slightly complex index that I need over a RavenDB document
given this document definition like:
public class PriceDocument
{
public string Id { get; set; }
public Guid PriceId { get; set; }
public decimal Price { get; set; }
public DateTime? PricingDate { get; set; }
public string Source { get; set; }
public int Version { get; set; }
}
I need to get all the products for a given productId (I can do that when I query)
that are unique by PricingDate (latest) and Source
So given the following data:
var priceDocument = new PriceDocument {
Price = 1m,
Id = productId + "/1",
PricingDate = new DateTime(2011, 4, 1, 8, 0, 0),
PriceId = productId,
Source = "Bloomberg",
Version = 1
};
var priceDocument1 = new PriceDocument {
Price = 1m,
Id = productId + "/2",
PricingDate = new DateTime(2011, 4, 1,9,0,0),
PriceId = productId,
Source = "Bloomberg",
Version = 1
};
I should get as a result priceDocument1, since its latest.
So far I have an index defined like this:
Map = docs =>
from priceDocument in docs
select new {
PricingDate = priceDocument.PricingDate,
PricingSource = priceDocument.Source,
Price = priceDocument.Price,
PriceId = priceDocument.PriceId
};
Reduce = results =>
from result in results
group result by new { result.PricingDate, result.Source } into price
select new {
PricingDate = price.Max(p => price.Key.PricingDate),
PricingSource = price.Key.Source,
};
But it doesnt work at run time, I'm getting an AbstractIndexingExecuter||8||Failed to index documents for index (my index name)
I've recreated this sample in a separate project and I can see that in stats in Raven Studio that I get the error:
Cannot implicitly convert type 'System.DateTimeOffset' to 'int' changed the DateTime? to DateTime
And no luck.
I switched from using the date to use the I can rely on it incrementing so now the index looks like this:
Map = docs =>
from priceDocument in docs
select new {
PricingDate = priceDocument.PricingDate,
PricingSource = priceDocument.Source,
ProductId = priceDocument.ProductId,
ProductVersion = priceDocument.Version
};
Reduce = results =>
from result in results
group result by new {
result.PriceId,
result.PricingDate,
result.Source,
result.Version
} into price
select new {
PricingDate = price.Key.PricingDate,
PricingSource = price.Key,
ProductVersion = price.Max(p=> price.Key.Version)
};
Now that throws no errors, however it also gives no results.

Answer 1

It should probably be this:
PricingDate = price.Max(p => (DateTimeOffset)price.Key.PricingDate)
But what you want doesn't require a map reduce index. You can get that by just using:
session.Query<PriceDocument>()
.Where(x=>x.ProduceId == prodId)
.OrderByDescending(x=>x.PriceDate)
.FirstOrDefault();
The reason your Map/Reduce index doesn't work is that you have different outputs for the map & reduce functions.

Answer 2

Trying changing this line in the Reduce part of the index, from
PricingDate = price.Max(p => price.Key.PricingDate)
to
PricingDate = price.Max(p => (int)price.Key.PricingDate)