EF-Linq表达式并使用整数列表来获得最佳性能

Question

So I have a list(table) of about 100k items and I want to retrieve all values that match a given list.

I have something like this. the Table Sections key is NOT a primary key, so I'm expecting each value in listOfKeys to return a few rows.

List<int> listOfKeys = new List<int>(){1,3,44};
var allSections = Sections.Where(s => listOfKeys.Contains(s.id));

I don't know if it makes a difference but generally listOfKeys will only have between 1 to 3 items.

I'm using the Entity Framework.

So my question is, is this the best / fastest way to include a list in a linq expression? I'm assuming that it isn't better to use another .NET ICollection data object. Should I be using a Union or something?

Thanks

Answer 1

Suppose the listOfKeys will contain only small about of items and it's local list (not from database), like <50, then it's OK. The query generated will be basically WHERE id in (...) or WHERE id = ... OR id = ... ... and that's OK for database engine to handle it.

Answer 2

A Join would probably be more efficient:

var allSections =
    from s in Sections
    join k in listOfKeys on s.id equals k
    select s;

Or, if you prefer the extension method syntax:

var allSections = Sections.Join(listOfKeys, s => s.id, k => k, (s, k) => s);