Question

I wrote the following method that receives a list and updates the database based on certain criteria:

 public void UpdateInventoryGoods(List<InventoryGoods> list, int id)
        {
            int index = 0;

            var query = from inventoryGoods in context.InventoryGoods
                        where inventoryGoods.ParentId == id
                        select inventoryGoods;

            List<InventoryGoods> goodsList = query.ToList();

            using (var scope = new TransactionScope())
            {
                foreach (InventoryGoods i in list)
                {
                    foreach (InventoryGoods e in goodsList)
                    {
                        if (index == 30)
                        {
                            index = 0;
                            context.SubmitChanges();
                        }

                        if (e.Gid == i.Gid && !getEventId(e.Id).HasValue && !e.ActionOn.HasValue)
                        {
                            e.Action = i.Action;

                        }
                        else if ((e.Gid == i.Gid && getEventId(e.Id).HasValue) && (e.Action != i.Action || i.ActionOn == DateTime.MinValue))
                        {
                            e.Action = i.Action;
                            e.ActionOn = null;

                            var allEvents = from invent in context.InventoryGoodsEvents
                                            where invent.InventoryGood == e.Id
                                            select invent;

                            List<InventoryGoodsEvents> inventoryGoodsEventsList = allEvents.ToList();

                            var events = from g in context.GoodsEvent                                         
                                         select g;

                            List<GoodsEvent> goodsEventList = events.ToList();

                            foreach (InventoryGoodsEvents goodsEvent in inventoryGoodsEventsList)
                            {
                                context.InventoryGoodsEvents.DeleteOnSubmit(goodsEvent);

                                foreach (GoodsEvent ge in goodsEventList)
                                {
                                    if (ge.Id == goodsEvent.EventId)
                                    {
                                        ge.IsDeleted = true;
                                        ge.DeletedOn = DateTime.Now;
                                        ge.DeletedBy = System.Web.HttpContext.Current.User.Identity.Name;
                                    }
                                }                                
                            }




                        }
                        ++index;
                    }
                }
                context.SubmitChanges();
                scope.Complete();
            }

        }

        public int? getEventId(int InventoryGood)
        {


            var InventoryGoodsEvents = from i in context.InventoryGoodsEvents
                                       where i.InventoryGood == InventoryGood
                                       select i;

            List<InventoryGoodsEvents> lst = InventoryGoodsEvents.ToList();

            if (lst.Count() > 0)
            {
                return lst[0].EventId;
            }
            else
            {
                return null;
            }
        }

Though this method works well for about 500 or 1000 objects, it gets too slow or eventually times out when I feed it over 8000 objects or more.
So, where could I improve its performance a little?

Answer 1

Don’t call the database in a loop.

Try moving the queries outside the loops like this:

 public void UpdateInventoryGoods(List<InventoryGoods> list, int id)
 {
     int index = 0;

     var query = from inventoryGoods in context.InventoryGoods
                 where inventoryGoods.ParentId == id
                 select inventoryGoods;

     List<InventoryGoods> goodsList = query.ToList();

     using (var scope = new TransactionScope())
     {
         var allEvents = from invent in context.InventoryGoodsEvents
                         where goodsList.Contains(invent.InventoryGood)
                         select invent;

         List<InventoryGoodsEvents> inventoryGoodsEventsList = allEvents.ToList();

         var events = from g in context.GoodsEvent
                      select g;

         List<GoodsEvent> goodsEventList = events.ToList();

         foreach (InventoryGoods i in list)
         {
             foreach (InventoryGoods e in goodsList)
             {
                 if (index == 30)
                 {
                     index = 0;
                     context.SubmitChanges();
                 }

                 var eventId = getEventId(e.Id);
                 if (e.Gid == i.Gid && !eventId.HasValue && !e.ActionOn.HasValue)
                 {
                     e.Action = i.Action;

                 }
                 else if ((e.Gid == i.Gid && eventId.HasValue) && (e.Action != i.Action || i.ActionOn == DateTime.MinValue))
                 {
                     e.Action = i.Action;
                     e.ActionOn = null;

                     foreach (InventoryGoodsEvents goodsEvent in inventoryGoodsEventsList)
                     {
                         context.InventoryGoodsEvents.DeleteOnSubmit(goodsEvent);

                         foreach (GoodsEvent ge in goodsEventList)
                         {
                             if (ge.Id == goodsEvent.EventId)
                             {
                                 ge.IsDeleted = true;
                                 ge.DeletedOn = DateTime.Now;
                                 ge.DeletedBy = System.Web.HttpContext.Current.User.Identity.Name;
                             }
                         }
                     }
                 }
                 ++index;
             }
         }
         context.SubmitChanges();
         scope.Complete();
     }
 }