我目前处于拥有大数据的CosmosDB的情况。这个大数据由包含带有日期和双值的对象的文档组成。
我尝试做的是获取一个月的数据（提供约220K记录）并计算该月每天的双倍值的平均值。我现在可能拥有非常低效的代码。我正在寻找能够解决我问题的公式或更高效的代码。我无法想到解决方案，谷歌搜索也没有给我解决方案。
我目前的计算太慢了。我最好在不到一秒钟的时间内完成计算。
这是我们正在谈论的C＃Web API，连接到Azure CosmosDB。这是我目前的代码：
// GET api/values/{databasename}/<Guid>
[HttpGet("{database}/{id}")]
public IActionResult GetRange(string database, string id, [FromQuery] int
option, [FromQuery] string from, [FromQuery] string to)
{
try
{
DateTime.TryParse(from, out var dateFrom);
DateTime.TryParse(to, out var dateTo);
var comparison = DateTime.Compare(dateFrom, dateTo);
if (comparison >= 0)
{
return BadRequest("Given dates are incorrect.");
}
// Get the timespan for the given option.
var timespan = TimeSpanSelectionHelper.GetTimeSpanForOption(option);
var dataRange = _cosmosDbService.GetRange(database, id, from, to).ToList();
var result = from kvp in dataRange
let key = RoundToNearest(kvp.EventEnqueuedUtcTime, timespan)
group kvp by key
into grouping
select new {
grouping.Key,
Avg = (int) grouping.Average(x => x.Temperature),
Min = grouping.Min(x => x.Temperature),
Max = grouping.Max(x => x.Temperature)
};
var enumerable = result.ToArray();
var min = enumerable.Select(x => new CosmosDbRangeSelectionKeyValueJsonModel(x.Key, x.Min)).ToArray();
var avg = enumerable.Select(x => new CosmosDbRangeSelectionKeyValueJsonModel(x.Key, x.Avg)).ToArray();
var max = enumerable.Select(x => new CosmosDbRangeSelectionKeyValueJsonModel(x.Key, x.Max)).ToArray();
var model = new CosmosDbRangeSelectionJsonModel(min, avg, max);
return Ok(model);
}
catch (DocumentClientException de)
{
var baseException = de.GetBaseException();
var message = string.Format("{0} error occurred: {1}, Message: {2}", de.StatusCode, de.Message,
baseException.Message);
return NotFound(message);
}
catch (Exception e)
{
var baseException = e.GetBaseException();
var message = string.Format("Error: {0}, Message: {1}", e.Message, baseException.Message);
return NotFound(message);
}
}
/// <summary>
/// </summary>
/// <param name="dt"></param>
/// <param name="d"></param>
/// <returns></returns>
private static DateTime RoundToNearest(DateTime dt, TimeSpan d)
{
var delta = dt.Ticks % d.Ticks;
// Do we round up?
var roundUp = delta > d.Ticks / 2;
var offset = roundUp ? d.Ticks : 0;
return new DateTime(dt.Ticks + offset - delta, dt.Kind);
}
编辑03-01-2018
我们必须密切注意这一点：