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前几天看了一个基于sqlserver的负载均衡与读写分离的软件Moebius,实现的方式还是不错的，这使得用sqlserver数据库的同学时有机会对数据库进行更有效的优化了
看着人有做的东西，自己也想用ＥＦ来实现一个读写分离，所以就有了本篇文章，仓储大叔读写分离的思路是：
1 用sqlserver自带的发布、订阅实现主，从数据库的结构，同步这事由sql帮我们完成
2 配置文件建立几个供只读的数据库连接串
3 建立ＳＱＬ命令拦截器
4 修改大叔的DbContextRepository基数，添加拦截行为
5 测试，搞定
有了上面的想法，咱就可以干事了，第一步不用说了，可以自己百度，从第２步说起
<!-- 只写-->
<add name="backgroundEntities" connectionString="metadata=res://*/background.csdl|res://*/background.ssdl|res://*/background.msl;provider=System.Data.SqlClient;provider connection string="data source=.;initial catalog=background;persist security info=True;user id=sa;password=zzl123;multipleactiveresultsets=True;application name=EntityFramework"" providerName="System.Data.EntityClient" />
<!-- 只读-->
<add name="backgroundEntitiesRead" connectionString="metadata=res://*/background.csdl|res://*/background.ssdl|res://*/background.msl;provider=System.Data.SqlClient;provider connection string="data source=.;initial catalog=background_Read1;persist security info=True;user id=sa;password=zzl123;multipleactiveresultsets=True;application name=EntityFramework"" providerName="System.Data.EntityClient" />
/// <summary>
/// SQL命令拦截器
/// </summary>
public class NoLockInterceptor : DbCommandInterceptor
{
private static readonly Regex _tableAliasRegex =
new Regex(@"(?<tableAlias>AS \[Extent\d+\](?! WITH \(NOLOCK\)))",
RegexOptions.Multiline | RegexOptions.IgnoreCase);
[ThreadStatic]
public static bool SuppressNoLock;
public override void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
{
string conn = command.Connection.ConnectionString;
base.NonQueryExecuting(command, interceptionContext);
}
public override void ScalarExecuting(DbCommand command,
DbCommandInterceptionContext<object> interceptionContext)
{
command.Connection.Close();
command.Connection.ConnectionString = "data source=.;initial catalog=background_Read1;persist security info=True;user id=sa;password=zzl123;multipleactiveresultsets=True;application name=EntityFramework";
command.Connection.Open();
if (!SuppressNoLock)
{
command.CommandText =
_tableAliasRegex.Replace(command.CommandText, "${tableAlias} WITH (NOLOCK)");
}
}
public override void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
{
command.Connection.Close();
command.Connection.ConnectionString = "data source=.;initial catalog=background_Read1;persist security info=True;user id=sa;password=zzl123;multipleactiveresultsets=True;application name=EntityFramework";
command.Connection.Open();
if (!SuppressNoLock)
{
command.CommandText =
_tableAliasRegex.Replace(command.CommandText, "${tableAlias} WITH (NOLOCK)");
}
}
}
public DbContextRepository(IUnitOfWork db, Action<string> logger)
{
UnitWork = db;
Db = (DbContext)db;
Logger = logger;
((IObjectContextAdapter)Db).ObjectContext.CommandTimeout = 0;
//SQL语句拦截器
System.Data.Entity.Infrastructure.Interception.DbInterception.Add(new EntityFrameworks.Data.Core.Common.NoLockInterceptor());
EntityFrameworks.Data.Core.Common.NoLockInterceptor.SuppressNoLock = true;
}
原文链接1：
原文链接2：
EF6.0新特性-DbCommandInterceptor实现非SQL端读写分离
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原文地址：http://www.cnblogs.com/x-poior/p/5257015.html
