通过两个整数键存储和检索值的最快方法

Question

我需要超级快速存储并通过两个整数键检索值.

所以我有输入值uint Id1, uint Id2,需要得到uint Count.

我也知道最大值Id1和Id2(约为5 000 000).

我目前的实现大约占应用程序工作时间的70%,可能需要几天时间.

它只是使用标准的.net词典,当然可以改进.但我想这是计算机科学中非常有用的操作,毫无疑问存在更高效的算法.

这是我的实施

void Main()
{
    var rep = new Repository();

    var sw = new Stopwatch();

    sw.Start();

    for (uint i = 0; i < 10000; i++)
    {
        for (uint j = 0; j < 1000; j++)
        {
            rep.Add(new DomainEntity(){Id1 = i, Id2 = j, Count = 1});
        }
    }

    for (uint i = 0; i < 10000; i++)
    {
        for (uint j = 0; j < 1000; j++)
        {
            rep.GetDomainEntityByIds(i,j);
        }
    }

    sw.Stop();
    Console.WriteLine ("Elapsed:{0}", sw.Elapsed);
}

public class Repository
{
        private readonly Dictionary<Tuple<UInt32, UInt32>, UInt32> _dictStore;

        public Repository()
        {
            _dictStore = new Dictionary<Tuple<uint, uint>, uint>();
        }

        public uint Add(DomainEntity item)
        {
            var entry = MapToTableEntry(item);
            _dictStore.Add(entry.Key,entry.Value);
            return 0;
        }

        public void Update(DomainEntity item)
        {
            var entry = MapToTableEntry(item);
            _dictStore[entry.Key] = entry.Value;
        }

        public IEnumerable<DomainEntity> GetAllItems()
        {
            return _dictStore.Select(MapToDomainEntity);
        }

        public DomainEntity GetDomainEntityByIds(uint articleId1, uint articleId2)
        {
            var tuple = new Tuple<uint, uint>(articleId1, articleId2);

            if (_dictStore.ContainsKey(tuple))
            {
                return MapToDomainEntity(new KeyValuePair<Tuple<uint, uint>, uint>(tuple, _dictStore[tuple]));
            }

            return null;
        }

        private KeyValuePair<Tuple<uint, uint>, uint> MapToTableEntry(DomainEntity item)
        {
            return new KeyValuePair<Tuple<uint, uint>, uint>(new Tuple<uint, uint>(item.Id1,item.Id2), item.Count);
        }

        private DomainEntity MapToDomainEntity(KeyValuePair<Tuple<uint, uint>, uint> entry)
        {
            return new DomainEntity
            {
                Id1 = entry.Key.Item1,
                Id2 = entry.Key.Item2,
                Count = entry.Value,
            };
        }
}

public class DomainEntity
{
        public uint Id1 { get; set; }
        public uint Id2 { get; set; }
        public uint Count { get; set; }
}

Answer 1

一个小的(？)改进,你可以TryGetValue用来避免两次查找字典:

public DomainEntity GetDomainEntityByIds(uint articleId1, uint articleId2)
{
    var tuple = new Tuple<uint, uint>(articleId1, articleId2);
    uint value;
    if (_dictStore.TryGetValue(tuple, out value))
    {
        return MapToDomainEntity(new KeyValuePair<Tuple<uint, uint>, uint>(tuple, value));
    }

    return null;
}