EF Core 3.0.Include() 鏈比 2.2 長約 5-10 倍

Question

我在處理包含大量鏈式.Include()的大型 EF Core 查詢時遇到問題。 我有一個看起來像這樣的 linq 查詢：

_context.Equipment.Include(x => x.Group)
                .Include(x => x.Status)
                .Include(x => x.Area)
                .Include(x => x.EquipmentType)
                .Include(x => x.Parts).ThenInclude(x => x.ChildrenParts)
                .Include(x => x.Parts).ThenInclude(x => x.ParentParts)
                .Include(x => x.Parts).ThenInclude(x => x.Vendor)
                .Include(x => x.Notes)
                .Include(x => x.Department)
                .Include(x => x.PMaintenance)
                .Include(x => x.SystemInfo).ThenInclude(x => x.SystemUsers)
                .Include(x => x.SystemInfo).ThenInclude(x => x.Frameworks)
                .Include(x => x.SystemInfo).ThenInclude(x => x.VideoCards)
                .Include(x => x.SystemInfo).ThenInclude(x => x.StorageDrives)
                .Include(x => x.SystemInfo).ThenInclude(x => x.Software)
                .Include(x => x.SystemInfo).ThenInclude(x => x.NetworkAdapters)
                .Include(x => x.SystemInfo).ThenInclude(x => x.Printers)
                .Include(x => x.MaintenanceHours)
                .Include(x => x.Attachments)
                .Include(x => x.Request)
                .FirstOrDefault(x => x.EquipmentId == id);

在 EF Core 2.2 中，這需要不到幾秒鍾的時間來評估。 現在在 EF Core 3.0 上，大約需要 15 秒才能完成。 EF Core 3 是怎么回事？ 我在這里讀到 ef 現在為每個 linq 查詢創建一個 sql 語句，但我看不出該語句在這種情況下會如何變化。 我可以對這個查詢做些什么來減少執行時間嗎？

編輯：這是在 SQL 服務器 v11.0.3

Answer 1

像這樣試試。 您可能需要更改一些“Select”和“SelectMany”選項以及 Id 字段名稱，因為您沒有發布上下文。`

var query = _context.Equipment.Include(x => x.Group)
            .Include(x => x.Status)
            .Include(x => x.Area)
            .Include(x => x.EquipmentType)
            .Include(x => x.Notes)
            .Include(x => x.Department)
            .Include(x => x.PMaintenance)
            .Include(x => x.MaintenanceHours)
            .Include(x => x.Attachments)
            .Include(x => x.Request).FirstOrDefault(x => x.EquipmentId == id);

            query.Include(x => x.Parts).ThenInclude(x => x.ChildrenParts).SelectMany(x => x.Parts).Where(a => query.Select(q => q.PartsId).Contains(a.Id)).Load();
            query.SelectMany(x => x.Parts).SelectMany(x => x.ChildrenParts).Load();
            query.SelectMany(x => x.Parts).SelectMany(x => x.ParentParts).Load();
            query.SelectMany(x => x.Parts).Select(x => x.Vendor).Load();
            query.Include(x => x.SystemInfo).ThenInclude(x => x.SystemUsers).SelectMany(x => x.SystemInfo).Where(a => query.Select(q => q.SystemInfoId).Contains(a.Id)).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.Frameworks).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.VideoCards).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.StorageDrives).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.Software).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.NetworkAdapters).Load();
            query.SelectMany(x => x.SystemInfo).SelectMany(x => x.Printers).Load();

            query.ToList();

希望這可以幫助。