实体框架查询太慢了

Question

I am new to entity framework and love the simplicity but am having some trouble with speed. I think I might be using the lazy loading incorrectly but having a hard time wrapping my head around it. I have separated my data model layer and business entity layer, and use a function to create the business entity from my data model. In this function I iterate over the different nested entities to create their corresponding models. Ok, enough rambling here is some code:

IM_ITEM.cs (Product data model)

public partial class IM_ITEM
{
    public IM_ITEM()
    {
        this.IM_INV = new HashSet<IM_INV>();
        this.IM_BARCOD = new HashSet<IM_BARCOD>();
        this.IM_GRID_DIM_1 = new HashSet<IM_GRID_DIM_1>();
        this.IM_GRID_DIM_2 = new HashSet<IM_GRID_DIM_2>();
        this.IM_GRID_DIM_3 = new HashSet<IM_GRID_DIM_3>();
        this.IM_PRC = new HashSet<IM_PRC>();
    }

    public string ITEM_NO { get; set; }
    public string DESCR { get; set; }
    // many more properties...

    public virtual ICollection<IM_INV> IM_INV { get; set; }
    public virtual ICollection<IM_BARCOD> IM_BARCOD { get; set; }
    public virtual ICollection<IM_GRID_DIM_1> IM_GRID_DIM_1 { get; set; }
    public virtual ICollection<IM_GRID_DIM_2> IM_GRID_DIM_2 { get; set; }
    public virtual ICollection<IM_GRID_DIM_3> IM_GRID_DIM_3 { get; set; }
    public virtual ICollection<IM_PRC> IM_PRC { get; set; }
}

Business entity creation method:

public static ProductEntity FromEfObject(IM_ITEM obj) {
    var product = new ProductEntity {
        ItemNumber = obj.ITEM_NO,
        StyleNumber = obj.VEND_ITEM_NO,
        Title = obj.DESCR_UPR,
        LongName = obj.ADDL_DESCR_1,
        ShortDescription = obj.DESCR,
        VendorCode = obj.ITEM_VEND_NO,
        Quarter = obj.ATTR_COD_2,
        Color = obj.PROF_ALPHA_2,
        Markdown = obj.PRC_1,
        Price = obj.REG_PRC ?? 0,
        Status = obj.STAT,
        DepartmentCode = obj.ATTR_COD_1,
        DepartmentDigit = obj.ATTR_COD_1.Substring(0, 1),
        MixAndMatch = obj.MIX_MATCH_COD,
        Inventory = new Inventory(obj.IM_INV),
        Sizes = new List<ProductSize>(),
        Widths = new List<ProductSize>(),
        Lengths = new List<ProductSize>(),
        Barcodes = new Dictionary<string, string>()
    };


    if (obj.IM_PRC.Any()) {
        var price = obj.IM_PRC.First();
        product.DnsPrice2 = price.PRC_2.GetValueOrDefault();
        product.DnsPrice3 = price.PRC_3.GetValueOrDefault();
    }

    foreach (var barcode in obj.IM_BARCOD) {
        product.Barcodes.Add(barcode.DIM_1_UPR, barcode.BARCOD);
    }

    foreach (var size in obj.IM_GRID_DIM_1) {
        product.Sizes.Add(ProductSize.FromEfObject(size));
    }

    foreach (var width in obj.IM_GRID_DIM_2) {
        product.Widths.Add(ProductSize.FromEfObject(width));
    }

    foreach (var length in obj.IM_GRID_DIM_3) {
        product.Lengths.Add(ProductSize.FromEfObject(length));
    }

    if (!product.Sizes.Any()) {
        product.Sizes.Add(new ProductSize());
    }

    if (!product.Widths.Any()) {
        product.Widths.Add(new ProductSize());
    }

    if (!product.Lengths.Any()) {
        product.Lengths.Add(new ProductSize());
    }

    return product;
}

And my method to retrieve the model:

public ProductEntity GetProductById(string itemNumber, int storeNumber) {
    var product = _unitOfWork
        .GetProductRepository(storeNumber)
        .GetQueryable()
        .FirstOrDefault(p => p.ITEM_NO == itemNumber);

    return product == null ? null : ProductEntity.FromEfObject(product);
}

And the GetQueryable method:

internal DbSet<TEntity> DbSet;
public GenericRepository(TContext context)
{
    Context = context;
    DbSet = context.Set<TEntity>();
}

public virtual IQueryable<TEntity> GetQueryable()
{
    IQueryable<TEntity> query = DbSet;
    return query;
}

A little more info.. I used database first modeling to create my data model, and the database I am testing against doesn't have a ton of data. Also, I tried using .Include() in my GetProductById method to load (eagerly I believe) but the slowed it down even further.

Am I doing something fundamentally wrong? Or is using EF going to be slow for a query like this.

EDIT: To prevent lazy loading I updated my query to:

    public ProductEntity GetProductById(string itemNumber, int storeNumber) {
        var product = _unitOfWork
            .GetProductRepository(storeNumber)
            .GetQueryable()
            .Include(p => p.IM_INV.Select(i => i.IM_INV_CELL))
            .Include(p => p.IM_BARCOD)
            .Include(p => p.IM_GRID_DIM_1)
            .Include(p => p.IM_GRID_DIM_2)
            .Include(p => p.IM_GRID_DIM_3)
            .Include(p => p.IM_PRC)
            .FirstOrDefault(p => p.ITEM_NO == itemNumber);

        return product == null ? null : ProductEntity.FromEfObject(product);
    }

When tracing, this gives me just one big nasty query that takes longer than using the lazy loading http://pastebin.com/LT1vTETb

Answer 1

You can optimize your query to avoid lazy loading. In this case, when you load an object from the database, you know you're going to have to map almost the entire object graph to memory. You're going to need to look up all of those foreign keys later anyway - it's faster to do it all as one query rather than letting lazy loading do the work. See here for more information.

It should look something like this:

public ProductEntity GetProductById(string itemNumber, int storeNumber) {
    var product = _unitOfWork
        .GetProductRepository(storeNumber)
        .GetQueryable()
        .Include(p => p.IM_BARCOD)
        .Include(p => p.IM_GRID_DIM_1)
        .Include(p => p.IM_GRID_DIM_2)
        .Include(p => p.IM_GRID_DIM_3)
        .Include(p => p.IM_PRC)
        .FirstOrDefault(p => p.ITEM_NO == itemNumber);

    return product == null ? null : ProductEntity.FromEfObject(product);
}

Note that if these foreign keys have their own foreign keys (ie IM_BARCOD has a collection of IM_OtherType) which you also need to map to your ProductEntity model, you should also include those. You can do it in line like this:

.Include(p => p.IM_BARCOD.Select(b => b.IM_OTHERTYPE))