Sawetara aspek ngoptimalake pitakon LINQ ing C#.NET kanggo MS SQL Server

LINQ mlebu .NET minangka basa manipulasi data anyar sing kuat. LINQ kanggo SQL minangka bagéan saka iku ngijini sampeyan kanggo komunikasi cukup trep karo DBMS nggunakake, contone, Entity Framework. Nanging, nggunakake cukup kerep, pangembang lali kanggo ndeleng apa jenis query SQL panyedhiya queryable, ing kasus Entity Framework, bakal generate.

Ayo katon ing rong titik utama nggunakake conto.
Kanggo nindakake iki, nggawe database Test ing SQL Server, lan nggawe loro tabel ing nggunakake pitakonan ing ngisor iki:

Nggawe tabel

USE [TEST]
GO

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Ref](
	[ID] [int] NOT NULL,
	[ID2] [int] NOT NULL,
	[Name] [nvarchar](255) NOT NULL,
	[InsertUTCDate] [datetime] NOT NULL,
 CONSTRAINT [PK_Ref] PRIMARY KEY CLUSTERED 
(
	[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[Ref] ADD  CONSTRAINT [DF_Ref_InsertUTCDate]  DEFAULT (getutcdate()) FOR [InsertUTCDate]
GO

USE [TEST]
GO

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Customer](
	[ID] [int] NOT NULL,
	[Name] [nvarchar](255) NOT NULL,
	[Ref_ID] [int] NOT NULL,
	[InsertUTCDate] [datetime] NOT NULL,
	[Ref_ID2] [int] NOT NULL,
 CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED 
(
	[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[Customer] ADD  CONSTRAINT [DF_Customer_Ref_ID]  DEFAULT ((0)) FOR [Ref_ID]
GO

ALTER TABLE [dbo].[Customer] ADD  CONSTRAINT [DF_Customer_InsertUTCDate]  DEFAULT (getutcdate()) FOR [InsertUTCDate]
GO

Saiki ayo isi tabel Ref kanthi nglakokake skrip ing ngisor iki:

Ngisi tabel Ref

USE [TEST]
GO

DECLARE @ind INT=1;

WHILE(@ind<1200000)
BEGIN
	INSERT INTO [dbo].[Ref]
           ([ID]
           ,[ID2]
           ,[Name])
    SELECT
           @ind
           ,@ind
           ,CAST(@ind AS NVARCHAR(255));

	SET @ind=@ind+1;
END 
GO

Ayo padha ngisi tabel Pelanggan kanthi nggunakake skrip ing ngisor iki:

Populating Tabel Pelanggan

USE [TEST]
GO

DECLARE @ind INT=1;
DECLARE @ind_ref INT=1;

WHILE(@ind<=12000000)
BEGIN
	IF(@ind%3=0) SET @ind_ref=1;
	ELSE IF (@ind%5=0) SET @ind_ref=2;
	ELSE IF (@ind%7=0) SET @ind_ref=3;
	ELSE IF (@ind%11=0) SET @ind_ref=4;
	ELSE IF (@ind%13=0) SET @ind_ref=5;
	ELSE IF (@ind%17=0) SET @ind_ref=6;
	ELSE IF (@ind%19=0) SET @ind_ref=7;
	ELSE IF (@ind%23=0) SET @ind_ref=8;
	ELSE IF (@ind%29=0) SET @ind_ref=9;
	ELSE IF (@ind%31=0) SET @ind_ref=10;
	ELSE IF (@ind%37=0) SET @ind_ref=11;
	ELSE SET @ind_ref=@ind%1190000;
	
	INSERT INTO [dbo].[Customer]
	           ([ID]
	           ,[Name]
	           ,[Ref_ID]
	           ,[Ref_ID2])
	     SELECT
	           @ind,
	           CAST(@ind AS NVARCHAR(255)),
	           @ind_ref,
	           @ind_ref;


	SET @ind=@ind+1;
END
GO

Mangkono, kita nampa loro tabel, siji kang wis luwih saka 1 yuta larik data, lan liyane wis luwih saka 10 yuta larik saka data.

Saiki ing Visual Studio sampeyan kudu nggawe proyek Visual C# Console App (.NET Framework):

Sabanjure, sampeyan kudu nambah perpustakaan kanggo Entity Framework kanggo sesambungan karo database.
Kanggo nambah, klik-tengen ing proyek banjur pilih Ngatur Paket NuGet saka menu konteks:

Banjur, ing jendhela manajemen paket NuGet sing katon, ketik tembung "Entity Framework" ing jendela telusuran banjur pilih paket Entity Framework lan instal:

Sabanjure, ing file App.config, sawise nutup unsur configSections, sampeyan kudu nambah blok ing ngisor iki:

<connectionStrings>
    <add name="DBConnection" connectionString="data source=ИМЯ_ЭКЗЕМПЛЯРА_MSSQL;Initial Catalog=TEST;Integrated Security=True;" providerName="System.Data.SqlClient" />
</connectionStrings>

Ing connectionString sampeyan kudu ngetik string sambungan.

Saiki ayo nggawe 3 antarmuka ing file sing kapisah:

1. Ngleksanakake antarmuka IBaseEntityID

   namespace TestLINQ
   {
       public interface IBaseEntityID
       {
           int ID { get; set; }
       }
   }
   

2. Implementasi antarmuka IBaseEntityName

   namespace TestLINQ
   {
       public interface IBaseEntityName
       {
           string Name { get; set; }
       }
   }
   

3. Implementasi antarmuka IBaseNameInsertUTCDate

   namespace TestLINQ
   {
       public interface IBaseNameInsertUTCDate
       {
           DateTime InsertUTCDate { get; set; }
       }
   }
   

Lan ing file sing kapisah, kita bakal nggawe BaseEntity kelas dhasar kanggo rong entitas kita, sing bakal kalebu lapangan umum:

Implementasi kelas basis BaseEntity

namespace TestLINQ
{
    public class BaseEntity : IBaseEntityID, IBaseEntityName, IBaseNameInsertUTCDate
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public DateTime InsertUTCDate { get; set; }
    }
}

Sabanjure, kita bakal nggawe rong entitas ing file sing kapisah:

1. Implementasi kelas Ref

   using System.ComponentModel.DataAnnotations.Schema;
   
   namespace TestLINQ
   {
       [Table("Ref")]
       public class Ref : BaseEntity
       {
           public int ID2 { get; set; }
       }
   }
   

2. Implementasi kelas Pelanggan

   using System.ComponentModel.DataAnnotations.Schema;
   
   namespace TestLINQ
   {
       [Table("Customer")]
       public class Customer: BaseEntity
       {
           public int Ref_ID { get; set; }
           public int Ref_ID2 { get; set; }
       }
   }
   

Saiki ayo nggawe konteks UserContext ing file sing kapisah:

Implementasi kelas UserContex

using System.Data.Entity;

namespace TestLINQ
{
    public class UserContext : DbContext
    {
        public UserContext()
            : base("DbConnection")
        {
            Database.SetInitializer<UserContext>(null);
        }

        public DbSet<Customer> Customer { get; set; }
        public DbSet<Ref> Ref { get; set; }
    }
}

Kita nampa solusi sing wis siap kanggo nganakake tes optimasi karo LINQ menyang SQL liwat EF kanggo MS SQL Server:

Saiki ketik kode ing ngisor iki menyang file Program.cs:

File Program.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace TestLINQ
{
    class Program
    {
        static void Main(string[] args)
        {
            using (UserContext db = new UserContext())
            {
                var dblog = new List<string>();
                db.Database.Log = dblog.Add;

                var query = from e1 in db.Customer
                            from e2 in db.Ref
                            where (e1.Ref_ID == e2.ID)
                                 && (e1.Ref_ID2 == e2.ID2)
                            select new { Data1 = e1.Name, Data2 = e2.Name };

                var result = query.Take(1000).ToList();

                Console.WriteLine(dblog[1]);

                Console.ReadKey();
            }
        }
    }
}

Sabanjure, ayo miwiti proyek kita.

Ing pungkasan karya, ing ngisor iki bakal ditampilake ing console:

Query SQL sing digawe

SELECT TOP (1000) 
    [Extent1].[Ref_ID] AS [Ref_ID], 
    [Extent1].[Name] AS [Name], 
    [Extent2].[Name] AS [Name1]
    FROM  [dbo].[Customer] AS [Extent1]
    INNER JOIN [dbo].[Ref] AS [Extent2] ON ([Extent1].[Ref_ID] = [Extent2].[ID]) AND ([Extent1].[Ref_ID2] = [Extent2].[ID2])

Yaiku, umume, pitakon LINQ ngasilake pitakon SQL menyang MS SQL Server DBMS kanthi apik.

Saiki ayo ngganti kondisi AND dadi UTAWA ing pitakon LINQ:

pitakon LINQ

var query = from e1 in db.Customer
                            from e2 in db.Ref
                            where (e1.Ref_ID == e2.ID)
                                || (e1.Ref_ID2 == e2.ID2)
                            select new { Data1 = e1.Name, Data2 = e2.Name };

Lan ayo miwiti aplikasi maneh.

Eksekusi bakal nabrak amarga kesalahan amarga wektu eksekusi perintah ngluwihi 30 detik:

Yen sampeyan ndeleng pitakon sing digawe dening LINQ:

, banjur sampeyan bisa nggawe manawa pilihan dumadi liwat produk Cartesian saka rong set (tabel):

Query SQL sing digawe

SELECT TOP (1000) 
    [Extent1].[Ref_ID] AS [Ref_ID], 
    [Extent1].[Name] AS [Name], 
    [Extent2].[Name] AS [Name1]
    FROM  [dbo].[Customer] AS [Extent1]
    CROSS JOIN [dbo].[Ref] AS [Extent2]
    WHERE [Extent1].[Ref_ID] = [Extent2].[ID] OR [Extent1].[Ref_ID2] = [Extent2].[ID2]

Ayo nulis ulang pitakon LINQ kaya ing ngisor iki:

Pitakon LINQ sing dioptimalake

var query = (from e1 in db.Customer
                   join e2 in db.Ref
                   on e1.Ref_ID equals e2.ID
                   select new { Data1 = e1.Name, Data2 = e2.Name }).Union(
                        from e1 in db.Customer
                        join e2 in db.Ref
                        on e1.Ref_ID2 equals e2.ID2
                        select new { Data1 = e1.Name, Data2 = e2.Name });

Banjur kita entuk pitakon SQL ing ngisor iki:

pitakon SQL

SELECT 
    [Limit1].[C1] AS [C1], 
    [Limit1].[C2] AS [C2], 
    [Limit1].[C3] AS [C3]
    FROM ( SELECT DISTINCT TOP (1000) 
        [UnionAll1].[C1] AS [C1], 
        [UnionAll1].[Name] AS [C2], 
        [UnionAll1].[Name1] AS [C3]
        FROM  (SELECT 
            1 AS [C1], 
            [Extent1].[Name] AS [Name], 
            [Extent2].[Name] AS [Name1]
            FROM  [dbo].[Customer] AS [Extent1]
            INNER JOIN [dbo].[Ref] AS [Extent2] ON [Extent1].[Ref_ID] = [Extent2].[ID]
        UNION ALL
            SELECT 
            1 AS [C1], 
            [Extent3].[Name] AS [Name], 
            [Extent4].[Name] AS [Name1]
            FROM  [dbo].[Customer] AS [Extent3]
            INNER JOIN [dbo].[Ref] AS [Extent4] ON [Extent3].[Ref_ID2] = [Extent4].[ID2]) AS [UnionAll1]
    )  AS [Limit1]

Sayange, ing pitakon LINQ mung ana siji syarat gabung, mula ing kene sampeyan bisa nggawe pitakon sing padha nggunakake rong pitakon kanggo saben kondisi banjur gabungke liwat Union kanggo mbusak duplikat ing antarane baris.
Ya, pitakon umume ora padha, kanthi nganggep manawa baris duplikat lengkap bisa dibalekake. Nanging, ing urip nyata, garis duplikat lengkap ora dibutuhake lan wong nyoba nyingkirake.

Saiki ayo mbandhingake rencana eksekusi saka rong pitakon iki:

1. kanggo CROSS JOIN, wektu eksekusi rata-rata yaiku 195 detik:
   
2. kanggo INNER JOIN-UNION wektu eksekusi rata-rata kurang saka 24 detik:
   

Nalika sampeyan bisa ndeleng saka asil, kanggo rong tabel karo mayuta-yuta cathetan, pitakonan LINQ optimized kaping pirang-pirang luwih cepet saka unoptimized.

Kanggo opsi karo AND ing kondisi, pitakonan LINQ saka formulir:

pitakon LINQ

var query = from e1 in db.Customer
                            from e2 in db.Ref
                            where (e1.Ref_ID == e2.ID)
                                 && (e1.Ref_ID2 == e2.ID2)
                            select new { Data1 = e1.Name, Data2 = e2.Name };

Pitakonan SQL sing bener bakal tansah digawe, sing bakal mlaku rata-rata sajrone 1 detik:

Uga kanggo LINQ kanggo manipulasi Obyek tinimbang pitakon kaya:

Pitakon LINQ (pilihan 1)

var query = from e1 in seq1
                            from e2 in seq2
                            where (e1.Key1==e2.Key1)
                               && (e1.Key2==e2.Key2)
                            select new { Data1 = e1.Data, Data2 = e2.Data };

sampeyan bisa nggunakake pitakon kaya:

Pitakon LINQ (pilihan 2)

var query = from e1 in seq1
                            join e2 in seq2
                            on new { e1.Key1, e1.Key2 } equals new { e2.Key1, e2.Key2 }
                            select new { Data1 = e1.Data, Data2 = e2.Data };

ing pundi:

Nemtokake rong susunan

Para[] seq1 = new[] { new Para { Key1 = 1, Key2 = 2, Data = "777" }, new Para { Key1 = 2, Key2 = 3, Data = "888" }, new Para { Key1 = 3, Key2 = 4, Data = "999" } };
Para[] seq2 = new[] { new Para { Key1 = 1, Key2 = 2, Data = "777" }, new Para { Key1 = 2, Key2 = 3, Data = "888" }, new Para { Key1 = 3, Key2 = 5, Data = "999" } };

, lan jinis Para ditetepake kaya ing ngisor iki:

Definisi Tipe Para

class Para
{
        public int Key1, Key2;
        public string Data;
}

Mangkono, kita nliti sawetara aspek ing ngoptimalake pitakon LINQ menyang MS SQL Server.

Sayange, malah pangembang .NET sing berpengalaman lan terkemuka lali yen dheweke kudu ngerti apa instruksi sing digunakake ing mburi layar. Yen ora, dheweke dadi konfigurator lan bisa nandur bom wektu ing mangsa ngarep nalika nggawe skala solusi piranti lunak lan kanthi owah-owahan cilik ing kahanan lingkungan eksternal.

Tinjauan singkat uga ditindakake kene.

Sumber kanggo tes - proyek kasebut dhewe, nggawe tabel ing database TEST, uga ngisi tabel kasebut kanthi data ana. kene.
Uga ing repositori iki, ing folder Plans, ana rencana kanggo nglakokake pitakon kanthi kahanan UTAWA.

Source: www.habr.com