Linq to SqlXml – GitHub

An early alpha of Linq to SqlXml is now available on github:

There is no documentation nor setup scripts so you’re on your own if you try it.
If you get it to run, be sure to add all indexes to the xml field – primary , secondary – path , secondary – value , secondary – property

Linq to SqlXML

I’m hacking along on my Document DB emulator ontop of Sql Server XML columns.

I have some decent Linq support in place now.
The following query:

var query = from order in orders
            //must have status shipped
            where order.Status >= OrderStatus.Shipped      
            //must contain foo or bar products
            where order.OrderDetails.Any(d => d.ProductNo == "Foo" || d.ProductNo == "Bar")
            //must have an order total > 100
            where order.OrderDetails.Sum(d => d.ItemPrice * d.Quantity) > 100 
            select order;

will yield the following Sql + XQuery to the Sql Server:

select *
from documents
where CollectionName = 'Order'  and 
--must have an order total > 100
          for $A in OrderDetails[1]/object/state 
                return ($A/ItemPrice[1] * $A/Quantity[1])) > xs:decimal(100))]') = 1) and 
--must contain foo or bar products
(documentdata.exist('/object/state[OrderDetails[1]/object/state[((ProductNo[1] = "Foo") or 
 (ProductNo[1] = "Bar"))]]') = 1) and 
--must have status shipped
(documentdata.exist('/object/state[(Status[1] >= xs:int(2))]') = 1)

Building a Document DB ontop of Sql Server

I’ve started to build a Document DB emulator ontop of Sql Server XML columns.
Sql Server XML columns can store schema free xml documents, pretty much like RavenDB or MongoDB stores schema free Json/Bson documents.

XML Columns can be indexed and queried using XPath queries.

So I decided to build an abstraction layer ontop of this in order to achieve similair ease of use.
I’ve built a serializer/deserializer that deals with my own XML structure for documents (state + metadata) and also an early Linq provider for querying.

Executing the following code:

var ctx = new DocumentContext("main");
var customers = ctx.GetCollection<Customer>().AsQueryable();

var query = from customer in customers
            where customer.Address.City == "abc" && customer.Name == "Acme Inc5"
            orderby customer.Name
            select customer;

var result = query.ToList();
foreach (var item in result)

Will yield the following SQL + XPath query:

select *

from documents

where CollectionName = 'Customer' and
   ((documentdata.exist('/object/state/Address/object/state/City/text()[. = "abc"]') = 1) and
    (documentdata.exist('/object/state/Name/text()[. = "Acme Inc5"]') = 1))

order by documentdata.value('((/object/state/Name)[1])','nvarchar(MAX)')

The result of the query will be returned to the client and then deserialized into the correct .NET type.