ChildrenQueryable 10 x slower than new Query

Hey,

when i’m doing

var isbnGroups = _isbnService.GetAllISBNGroups().ToList();

var list = new List<ISBNGroupModel>();
foreach (var group in isbnGroups)
{
    list.Add(new ISBNGroupModel()
    {
        BaseNumber = group.BaseNumber,
        Count = group.Count,
        AvailableCount = group.Numbers.ChildrenQueryable().Count()
    });
}
return Ok(list);

it takes about 700-900 ms, with 1 ISBN Group and 9999 ISBNs (Numbers)

when doing

var isbnGroups = _isbnService.GetAllISBNGroups().ToList();

var list = new List<ISBNGroupModel>();
foreach (var group in isbnGroups)
{
    var childrenCount = DB.Queryable<ISBN>().Count(x => x.ISBNGroup.ID == group.ID);
    list.Add(new ISBNGroupModel()
    {
        BaseNumber = group.BaseNumber,
        Count = group.Count,
        AvailableCount = childrenCount
    });
}
return Ok(list);

it takes about 48-172 ms…

Btw, is there a better way to count a Many Child Collection?

[dj-nitehawk]

released v8.10 with Many<T>.ChildrenCount() which does the above internally.

    count = group.Numbers.ChildrenCount()

will you let me know how fast this method works on your 10k isbn records? thanks!

[Seyden]

Oh btw, its around 35 ms, where my fastest hack implementation was 48 ms