Entity Framework Code First Fluent Api：向列添加索引

发布于 2024-12-18 02:12:05 字数 1398 浏览 2 评论 0原文

我正在运行 EF 4.2 CF，并希望在 POCO 对象中的某些列上创建索引。

举个例子，假设我们有这个员工类别：

public class Employee
{
  public int EmployeeID { get; set; }
  public string EmployeeCode { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

我们经常通过员工代码搜索员工，并且由于有很多员工，出于性能原因将其编入索引会很好。

我们可以用 Fluent api 来做到这一点吗？或者也许是数据注释？

我知道可以执行这样的 sql 命令：

context.Database.ExecuteSqlCommand("CREATE INDEX IX_NAME ON ...");

我非常希望避免这样的原始 SQL。

我知道这不存在，但正在寻找类似的东西：

class EmployeeConfiguration : EntityTypeConfiguration<Employee>
    {
        internal EmployeeConfiguration()
        {
            this.HasIndex(e => e.EmployeeCode)
                .HasIndex(e => e.FirstName)
                .HasIndex(e => e.LastName);
        }
    }

或者也许使用 System.ComponentModel.DataAnnotations ， POCO 可能看起来像这样（我再次知道这不存在）：

public class Employee
{
  public int EmployeeID { get; set; }
  [Indexed]
  public string EmployeeCode { get; set; }
  [Indexed]
  public string FirstName { get; set; }
  [Indexed]
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

任何人都有任何想法如何做到这一点，或者是否有任何计划实施一种方法来做到这一点，代码优先的方式？

更新： 正如 Robba 的回答中提到的，此功能在 EF 版本 6.1 中实现

原文

I'm running EF 4.2 CF and want to create indexes on certain columns in my POCO objects.

As an example lets say we have this employee class:

public class Employee
{
  public int EmployeeID { get; set; }
  public string EmployeeCode { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

We often do searches for employees by their EmployeeCode and since there are a lot of employees it would be nice to have that indexed for performance reasons.

Can we do this with fluent api somehow? or perhaps data annotations?

I know it is possible to execute sql commands something like this:

context.Database.ExecuteSqlCommand("CREATE INDEX IX_NAME ON ...");

I would very much like to avoid raw SQL like that.

i know this does not exist but looking for something along those lines:

class EmployeeConfiguration : EntityTypeConfiguration<Employee>
    {
        internal EmployeeConfiguration()
        {
            this.HasIndex(e => e.EmployeeCode)
                .HasIndex(e => e.FirstName)
                .HasIndex(e => e.LastName);
        }
    }

or maybe using System.ComponentModel.DataAnnotations the POCO could look like this (again i know this does not exist):

public class Employee
{
  public int EmployeeID { get; set; }
  [Indexed]
  public string EmployeeCode { get; set; }
  [Indexed]
  public string FirstName { get; set; }
  [Indexed]
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

Anyone have any ideas on how to do this, or if there are any plans to implement a way to do this, the code first way?

UPDATE: As mentioned in the answer by Robba, this feature is implemented in EF version 6.1

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℉絮湮 2024-12-25 02:12:05

EF 4.3 中引入迁移后，您现在可以在修改或创建表时添加索引。以下是的摘录来自 ADO.NET 团队博客的 EF 4.3 基于代码的迁移演练

namespace MigrationsCodeDemo.Migrations
{
    using System.Data.Entity.Migrations;

    public partial class AddPostClass : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "Posts",
                c => new
                    {
                        PostId = c.Int(nullable: false, identity: true),
                        Title = c.String(maxLength: 200),
                        Content = c.String(),
                        BlogId = c.Int(nullable: false),
                    })
                .PrimaryKey(t => t.PostId)
                .ForeignKey("Blogs", t => t.BlogId, cascadeDelete: true)
                .Index(t => t.BlogId)
                .Index(p => p.Title, unique: true);

            AddColumn("Blogs", "Rating", c => c.Int(nullable: false, defaultValue: 3));
        }

        public override void Down()
        {
            DropIndex("Posts", new[] { "BlogId" });
            DropForeignKey("Posts", "BlogId", "Blogs");
            DropColumn("Blogs", "Rating");
            DropTable("Posts");
        }
    }
}

这是添加索引的一种很好的强类型方法，这正是我第一次发布问题时所寻找的。

After Migrations was introduced in EF 4.3 you can now add indexes when modifying or creating a table. Here is an excerpt from the EF 4.3 Code-Based Migrations Walkthrough from the ADO.NET team blog

namespace MigrationsCodeDemo.Migrations
{
    using System.Data.Entity.Migrations;

    public partial class AddPostClass : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "Posts",
                c => new
                    {
                        PostId = c.Int(nullable: false, identity: true),
                        Title = c.String(maxLength: 200),
                        Content = c.String(),
                        BlogId = c.Int(nullable: false),
                    })
                .PrimaryKey(t => t.PostId)
                .ForeignKey("Blogs", t => t.BlogId, cascadeDelete: true)
                .Index(t => t.BlogId)
                .Index(p => p.Title, unique: true);

            AddColumn("Blogs", "Rating", c => c.Int(nullable: false, defaultValue: 3));
        }

        public override void Down()
        {
            DropIndex("Posts", new[] { "BlogId" });
            DropForeignKey("Posts", "BlogId", "Blogs");
            DropColumn("Blogs", "Rating");
            DropTable("Posts");
        }
    }
}

This is a nice strongly typed way to add the indexes, which was what i was looking for when i first posted the question.

Entity Framework Code First Fluent Api：向列添加索引

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