Question

I have a function that uses LINQ to get data from the database and then I call that function in another function to sum all the individual properties using .Sum() on each individual property. I was wondering if there is an efficient way to sum all the properties at once rather than calling .Sum() on each individual property. I think the way I am doing as of right now, is very slow (although untested).

public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange)
{
    IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange);
    
    int pageViews = query.Sum(q => q.PageViews);
    int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors);
    int visits = query.Sum(q => q.Visits);
    double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit);
    double bounceRate = (double)query.Sum(q => q.BounceRate);

    return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit);
}

private IQueryable<OminitureStats> GetOmnitureDataAsQueryable(int? fnsId, int dateRange)
{
    var yesterday = DateTime.Today.AddDays(-1);
    var nDays = yesterday.AddDays(-dateRange);

    if (fnsId.HasValue)
    {
        IQueryable<OminitureStats> query = from o in lhDB.omniture_stats
                                            where o.fns_id == fnsId
                                                    && o.date <= yesterday
                                                    && o.date > nDays
                                            select new OminitureStats ( 
                                                o.page_views.GetValueOrDefault(), 
                                                o.monthly_unique.GetValueOrDefault(),
                                                o.visits.GetValueOrDefault(),
                                                (double)o.bounce_rate.GetValueOrDefault()
                                            );
        return query;
    }
    return null;
}

public class OminitureStats
{
    public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate)
    {
        this.PageViews = PageViews;
        this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
        this.Visits = Visits;
        this.BounceRate = BounceRate;
        this.PagesPerVisit = Math.Round((double)(PageViews / Visits), 1);
    }

    public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate, double PagesPerVisit)
    {
        this.PageViews = PageViews;
        this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
        this.Visits = Visits;
        this.BounceRate = BounceRate;
        this.PagesPerVisit = PagesPerVisit;
    }

    public int PageViews { get; set; }
    public int MonthlyUniqueVisitors { get; set; }
    public int Visits { get; set; }
    public double PagesPerVisit { get; set; }
    public double BounceRate { get; set; }
}

Answer 1

IIRC you can do all the sums in one go (as long as the query is translated to SQL) with

var sums = query.GroupBy(q => 1)
                .Select(g => new
                {
                    PageViews = g.Sum(q => q.PageViews),
                    Visits = g.Sum(q => q.Visits),
                    // etc etc
                })
                .Single();

This will give you one object which contains all the sums as separate properties.