Using LINQ to pull collection until aggregate condition met - sql

Question

At a high level, I need a query that can pull a subset of records based on the sum of a column, just like Linq: How to query items from a collection until the sum reaches a certain value.
However, the key difference is that he's already got his records in an object, and I don't and can't. My table can have millions of records. If I build my query the way he did, I get this error:
"A lambda expression with a statement body
cannot be converted to an expression tree"
Which makes sense after researching it, LINQ can't turn the answer in the above referenced question into valid SQL.
I'm going to make a hypothetical table that represents my situation.
Order Id | Cookie Name | Qty
1 Sugar 5
2 Snickerdoodle 4
3 Chocolate chip 8
4 Snickerdoodle 10
5 Snickerdoodle 5
Given this sample, I need to write a query that grabs the first X orders of Snickerdoodle until the summed Qty exceedes an input from the parameter (i.e. If the user chooses 13, it would return records 2 & 4 ).
I'm using Nhibernate.Linq, because I'm more comfortable in LINQ. I'm completely open to ICreate if the need arises.
As a side note, I'm interested in this as a concept as well as a direct problem. Even though I need a Sum, there has to be a way to do something akin to a takewhile that executes until a condition is met.

Answer 1

pragmatic approach
int needed = ...;
int actual = 0;
int page = 0;
const int pagesize = 20; // set to some sensible value, eg. the pagesize of the grid shown to the user
var results = new List<CookieOrder>();
while (actual < needed)
{
var partialResults = session.Query<CookieOrder>()
.Where(c => c.Name == "Snickerdoodle")
.OrderBy(c => c.Id)
.Skip(page * pagesize)
.Take(pagesize)
.ToList();
for(int i = 0; i < partialResults.Length && actual < needed; i++)
{
results.Add(partialResults[i]);
actual = partialResults[i].Quantity;
}
page++;
}
return results;