Guid default equality comparer

This is a discussion on Guid default equality comparer within the C# Programming forums, part of the General Programming Boards category; I have a dictionary which maps a Guid to Orders, it contains like 350000 orders Code: Dictionary<Guid, Order> htPreOrders = ...

  1. #1
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    Guid default equality comparer

    I have a dictionary which maps a Guid to Orders, it contains like 350000 orders

    Code:
    Dictionary<Guid, Order> htPreOrders = new Dictionary<Guid, PreOrder>(350000);
    Im trying to optimize it by replacing the IEqualityComparer by a custom one.

    Code:
            class Comp : IEqualityComparer<Guid>
            {
                public bool Equals(Guid x, Guid y)
                {
                    return x == y;
                }
                public int GetHashCode(Guid obj)
                {
                    return obj.GetHashCode();
                }
    
    Dictionary<Guid, Order> htPreOrders = new Dictionary<Guid, PreOrder>(350000, new Comp());
    would this be faster, or is that the same as the default equality comparer of Guid?

  2. #2
    the hat of redundancy hat nvoigt's Avatar
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    I don't see any reason why it would be faster. You need to check if this part of your program actually needs optimization, because you seem to be guessing a lot.
    hth
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    Im learning c# and making software at the same time. So ye Im guessing a lot on how to optimize things but this part needs optimization. Its a database which takes half an hour to retrieve which uses guids for primary keys. But anyway this was not an improvement.

  4. #4
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    Quote Originally Posted by KIBO View Post
    Im learning c# and making software at the same time. So ye Im guessing a lot on how to optimize things but this part needs optimization. Its a database which takes half an hour to retrieve which uses guids for primary keys. But anyway this was not an improvement.
    I would doubt it's taking 30 minutes to actually do the comparison(s) needed in a lookup - with the number of objects in your "database" your hash collisions should be relatively small, so most of the lookups will be O(1).
    I'd rethink your paradigm - local variables are not intended to replace an actual database; use a real database if you need one.
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