在foreach循环中添加或更新实体需要太长时间才能调用SaveChanges（）？ [英] Adding to or updating an entity in a foreach loop takes too long time before calling SaveChanges()?

问题描述

我有这种方法可以保存带有相关项（多对多关系）的实体，

I have this method that saves an entity with its related items (many-to-many relationship),

private static void Save<T>(TbCommonHistoryLog log, List<T> lstDetails) where T : IHasSerial
{   
    foreach (var item in lstDetails.OrderBy(x => x.Serial))
    {
        var ser = SerializeObject(item);
        var record = oContext.TbHistoryLog_Lists.FirstOrDefault(x => x.ListObjectJson == ser);
        if (record == null) //add new list item
        {
            TbCommonHistoryLog_Lists listObject = new TbCommonHistoryLog_Lists()
            {
                ListObjectJson = SerializeObject(item)
            };
            var details = new TbCommonHistoryLogDetails { TbHistoryLog = log, TbHistoryLog_Lists = listObject };
            oContext.TbHistoryLogDetails.Add(details);
        }
        else //attach an existing list item
        {
            var o = oContext.TbHistoryLog_Lists.Find(record.Id);
            oContext.TbHistoryLog_Lists.Attach(o);
            var details = new TbCommonHistoryLogDetails { TbHistoryLog = log, TbHistoryLog_Lists = o };
            oContext.TbHistoryLogDetails.Add(details);
        }
    }
    oContext.BulkSaveChanges();
}

我有两个表： TbCommonHistoryLog ， TbCommonHistoryLog_Lists ，它们之间存在多对多关系，联接表为 TbCommonHistoryLogDetails ，
我在这里所做的是对主从模型的审计，所有审计都在数据库中序列化为JSON，我将head对象保存在 TbCommonHistoryLog 表中，并保存每个列表 TbHistoryLog_Lists 表中的项目，在上面的方法中，我检查列表项是否已存在于数据库中或避免重复。
，但是此过程耗时超过15秒，这是一个很长的时间，我无法弄清楚我在做什么错..请帮助？

I have two tables: TbCommonHistoryLog, TbCommonHistoryLog_Lists, that are in many to many relationship, the joining table is TbCommonHistoryLogDetails, What I'm doing here is an auditing for master-detail models, all audits are serialized to JSON in DB, I save the head object in the TbCommonHistoryLog table, and every list item in the TbHistoryLog_Lists table, in the mthod above I check if the list item is already exists in the database or not to avoid duplicating. but this process takes more than 15 seconds which is a very long time, I can't figure out what am I doing wrong here.. please help?

推荐答案

对于集合中的每个项目，您都在查询数据库。我的建议是将记录保存到var中，然后询问该变量是否在数据库中。

For every single item in collection you're querying database. My suggestion is to save records in var, then ask the variable if the item is in database.

var databaseRecords = oContext.TbHistoryLog_Lists.ToList();

然后在循环中：

var record = databaseRecords.FirstOrDefault(x => x.ListObjectJson == ser);

这篇关于在foreach循环中添加或更新实体需要太长时间才能调用SaveChanges（）？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！