Question

我正在尝试通过将多个集合合并为一个（下面的代码段中的callQuery）然后从合并集合（dataCopy）更新另一个列表来使用LINQ来完成大型操作。

代码以这种方式构造的原因是在内存中处理这些计算（尽管其中一些可能更适合作为数据库操作），因为数据来自SQL和NoSQL DB源。

它有效，但它的速度非常慢。完成以下大小的列表需要10秒钟以上：

dataCopy = 397行（此对象将在循环中更新）
callQuery = 792（此对象是SQL / NoSQL数据集的预计合并）
holidayStructureList = 11（对象包含关于一天是否是假日的信息）
HourValuePairs = 24（对象将始终为24个值，包含特定日期的小时：值对）

我是否完全错了这个或者我的代码中有什么东西可以解决这个问题？

dataCopy.ForEach(dc =>
            {
                //Apply Cost and Rate to each Hour:Value pair 
                dc.HourValuePairs.ForEach(dchv => {
                      var matchQuery =
                            (
                                //If there were holidays...
                                holidayStructureList != null
                                ?
                                    //If the day is a holiday
                                    (holidayStructureList.Select(h => h.Date.Date).Contains(dc.Date.Date)) 
                                    ?
                                        //Then ensure that the IsHoliday flag is set
                                        callQuery.Where(
                                            cq => cq.Date.Date == dc.Date.Date && cq.PDay.ToLower() == "holiday"
                                            && dc.Date >= cq.StartDate && dc.Date <= cq.EndDate
                                            && dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                            && cq.IsHoliday == true
                                        )
                                        :
                                            //Else, it's a regular day
                                            callQuery.Where(
                                                cq => cq.Date.Date == dc.Date.Date && cq.PDay.ToLower() == dc.Date.DayOfWeek.ToString().ToLower()
                                                && dc.Date >= cq.StartDate && dc.Date <= cq.EndDate
                                                && dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                                && cq.IsHoliday == false
                                            )
                                    :
                                    //No holidays found in the collection, all days are non-holidays
                                    callQuery.Where(
                                        cq => cq.Date.Date == dc.Date.Date && cq.PDay.ToLower() == dc.Date.DayOfWeek.ToString().ToLower()
                                        && dc.Date >= cq.StartDate && dc.Date <= cq.EndDate
                                        && dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                        && cq.IsHoliday == false
                                    )
                            );

                      dchv.Type = matchQuery.Select(x => x.TypeIndexes).FirstOrDefault();
                      dchv.Cost = decimal.Round(matchQuery.Select(x => x.Rate).FirstOrDefault() * (dchv.value == null ? 0 : Convert.ToDecimal(dchv.value)), 2);
                      dchv.Label = matchQuery.Select(x => x.Label).FirstOrDefault();
                });

                //Apply Type Grouping
                var types = dc.HourValuePairs.GroupBy(x => x.Type).Select(y => new
                {
                    Index = y.Key,
                    Value = y.Sum(z => z.value)
                });

                dc.ValueType1 = types.Where(x => x.TypeId == 1).Select(x => x.Value).FirstOrDefault() ?? 0m;
                dc.ValueType2 = types.Where(x => x.TypeId == 2).Select(x => x.Value).FirstOrDefault() ?? 0m;
                dc.ValueType2 = types.Where(x => x.TypeId == 3).Select(x => x.Value).FirstOrDefault() ?? 0m;
            });

感谢您的帮助！

修改

根据Omada的评论，我尝试了以下内容，将查询执行时间降低到1.25秒。

dataCopy.ForEach(dc =>
            {
                var callQueryWithHolidays = callQuery.Where(
                                            cq => cq.Date.Date == dc.Date.Date && cq.TOUProfileDay.ToLower() == "holiday"
                                            && dc.Date >= cq.EffectiveDate && dc.Date <= cq.EndDate
                                            && cq.IsHoliday == true
                                        ).ToList();

                var callQueryWithoutHolidays = callQuery.Where(
                                                cq => cq.Date.Date == dc.Date.Date && cq.TOUProfileDay.ToLower() == dc.Date.DayOfWeek.ToString().ToLower()
                                                && dc.Date >= cq.EffectiveDate && dc.Date <= cq.EndDate
                                                && cq.IsHoliday == false
                                            ).ToList();

                //Apply Cost and Rate to each Hour:Value pair 
                dc.HourValuePairs.ForEach(dchv => {
                      var matchQuery =
                            (
                                //If there were holidays...
                                holidayStructureList != null
                                ?
                                    //If the day is a holiday
                                    (holidayStructureList.Select(h => h.Date.Date).Contains(dc.Date.Date)) 
                                    ?
                                        //Then ensure that the IsHoliday flag is set
                                        callQueryWithHolidays.Where(
                                            cq => dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                        )
                                        :
                                            //Else, it's a regular day
                                            callQueryWithoutHolidays.Where(
                                                cq => dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                            )
                                    :
                                    //No holidays found in the collection, all days are non-holidays
                                    callQueryWithoutHolidays.Where(
                                        cq => dchv.h >= cq.ItemStartHour && dchv.h <= cq.ItemEndHour
                                    )
                            );

                      dchv.Type = matchQuery.Select(x => x.TypeIndexes).FirstOrDefault();
                      dchv.Cost = decimal.Round(matchQuery.Select(x => x.Rate).FirstOrDefault() * (dchv.value == null ? 0 : Convert.ToDecimal(dchv.value)), 2);
                      dchv.Label = matchQuery.Select(x => x.Label).FirstOrDefault();
                });

                //Apply Type Grouping
                var types = dc.HourValuePairs.GroupBy(x => x.Type).Select(y => new
                {
                    Index = y.Key,
                    Value = y.Sum(z => z.value)
                });

                dc.ValueType1 = types.Where(x => x.TypeId == 1).Select(x => x.Value).FirstOrDefault() ?? 0m;
                dc.ValueType2 = types.Where(x => x.TypeId == 2).Select(x => x.Value).FirstOrDefault() ?? 0m;
                dc.ValueType2 = types.Where(x => x.TypeId == 3).Select(x => x.Value).FirstOrDefault() ?? 0m;
            });

Answer 1

如上面的评论：

在您的callQuery.Where来电中，您正在过滤是否是假期。你可以事先在外面做 dataCopy.ForEach循环并制作两个已过滤的列表。那你就不会必须遍历内循环中的所有792。

这似乎对你有用！ :)如果你需要低于1.25秒，你可能需要做@Alexei Levenkov建议并开始制作你的数据字典。

Lambda - 在多个List <t>上嵌套forEach操作非常慢

1 个答案: