Question

According to this site the ordering algorithm for hacker news goes something like this:

(p – 1) / (t + 2)^1.5

Description:

Votes divided by age factor

p = votes (points) from users. t =
time since submission in hours.

p is subtracted by 1 to negate
submitters vote. age factor is (time
since submission in hours plus two) to
the power of 1.5.

Given a table structure similar to this:

Item
ID
Link
DatePosted

Item_Votes
ItemID
Value

What would be the best way to implement the algorithm using linq to sql, would I be able to write the query entirely in linq or would I need to use a stored procedure or something else.

Update. Ended up using the code below based off TJB’s answer:

    var votesQuery =
        from i in db.Items
        join v in db.Item_Votes on i.ItemID equals v.ItemID
        orderby
            (double)(v.Value - 1) /
                    Math.Pow(
                        (DateTime.Now - i.DatePosted.Value).TotalHours + 2,
                    1.5) descending
        select i;

Answer 1

Using 2 1 Linq queries (there’s probably still a more efficent way)

var votesQuery =
    from i in items
    join v in votes on i.Id equals v.ItemId
    orderby
        (v.Value - 1) / 
                Math.Pow( 
                    (DateTime.Now - i.Posted).Add(new TimeSpan(2,0,0)).Hours, 
                1.5 )
    select new
    {
        Item = i,
        Vote = v
    };