Azure 中的跨上下文 LINQ 联接？

Question

我们目前正在将生产平台迁移到 Azure，因此我需要迁移我们所有的支持工具。以前，我们严重依赖数据适配器和存储过程，其中许多存储过程执行跨数据库连接。

随着我们迁移到 Azure，这些跨数据库连接都无法运行。我尝试将我们的数据适配器移动到实体框架，但我似乎无法让它们工作。相反，我收到一条错误消息，指出不允许跨上下文连接。其中许多查询依赖于来自多个数据库的数据，因此我只是想找出实现此操作的最佳方法。

我查看了其他几个要求类似解决方案的问题，但似乎没有一个非常适用于我的解决方案。

例如，下面是 SQL 中更简单的查询之一：

USE CustomerDB1234
SELECT DISTINCT u.[UserID]
  ,u.[UserLogin]
  ,u.[UserPhoneNumber]
  ,u.[UserPasswordHash]  
  , ISNULL(gl.[gl_login_name],'* no global login ID') AS [gl_login_name]
  ,gl.[gl_password_hash]
  ,gl.[gl_GUID]
  ,gl.[gl_Email_Validated]
  ,u.[usr_unit_set_id]
  ,oob.[oob_org_id]
FROM [dbo].[User] u WITH (NOLOCK)
LEFT JOIN [dbo].[OrganizationObjectBridge] oob WITH (NOLOCK) ON oob.[oob_object_type_id] = 9 AND oob.[oob_object_id]= u.UserID  
LEFT JOIN [MainServer].[MainDb].[dbo].[GlobalLoginCustomerBridge] glcb WITH (NOLOCK) ON glcb.[glcbr_user_id] = u.UserID
    AND glcb.[glcbr_customer_id] = dbo.efnGetCustomerID()
LEFT JOIN [MainServer].[MainDb].[dbo].[GlobalLogin] gl WITH (NOLOCK) ON gl.[gl_id] = glcb.[glcbr_gl_id]
WHERE ([UserID] = @userID OR @userID IS NULL)
    AND ([UserDisabled] = @isDisabled OR @isDisabled IS NULL)
ORDER BY [gl_login_name]

在 Linq 中，它看起来类似于：

List<User2> userList = new List<User2>();
using (var e = new eContext())
using (var context = new CustomerContext(CustomerID))
{
    var databaseConnections = e.DatabaseConnectionStrings;
    var customer = e.Customers.Select(n => new
    {
        ID = n.CustomerID,
        Name = n.CustomerName,
        Email = n.CustomerEmail,
        Website = n.CustomerWWW,
        Logo = n.CustomerLogo,
        DatabaseConnectionName = databaseConnections.FirstOrDefault(d => d.DatabaseConnectionID == n.DatabaseConnectionID).DatabaseConnectionName,
        DatabaseConnectionString = databaseConnections.FirstOrDefault(d => d.DatabaseConnectionID == n.DatabaseConnectionID).DatabaseConnectionString1,
        AccountNumber = n.CustomerAcctNumber
    }).FirstOrDefault(n => n.ID == CustomerID);

    userList = context.Users
        .Join(e.GlobalLoginCustomerBridges,
            u => u.UserID,
            glcb => glcb.glcbr_user_id,
            (u, glcb) => new { u, glcb })
            .Where(n => n.glcb.glcbr_customer_id == CustomerID)
        .Join(e.GlobalLogins,
            glcb => glcb.glcb.glcbr_gl_id,
            gl => gl.gl_id,
            (glcb, gl) => new { glcb, gl })
        .Join(context.OrganizationObjectBridges,
            glcb => glcb.glcb.u.UserID,
            oob => oob.oob_object_id,
            (glcb,oob) => new {glcb, oob})
            .Where(n=>n.oob.oob_object_type_id == 9)
       .Select(n => new
       {
           ID = n.glcb.glcb.u.UserID,
           GlobalLogin = n.glcb.gl.gl_login_name,
           FirstName = n.glcb.glcb.u.UserFirstName,
           MiddleName = n.glcb.glcb.u.UserMiddleName,
           LastName = n.glcb.glcb.u.UserLastName,
           GUID = n.glcb.gl.gl_GUID,
           UserID = n.glcb.gl.gl_id,
           HasSHA256Hash = n.glcb.gl.gl_password_hash_sha256 == null,
           Customer = customer,
           Organization = context.Organizations
               .Select(o => new
               {
                   ID = o.org_id,
                   Name = o.org_name,
                   ParentID = o.org_parent_id,
                   ExternalID = o.org_external_id,
                   Default = o.org_default,
                   Logo = o.org_logo,
                   URL = o.org_url,
                   PeerGroupID = o.org_peer_grp_id,
                   ExternalInfo = o.org_external_info
               }).Cast<Organization2>().FirstOrDefault(o=>o.ID == n.oob.oob_org_id)
    }).Cast<User2>().ToList();

}

Answer 1

两种方法：

1. 在内存中执行应用程序中的连接。根据查询，这或多或少是有效的。此外，所需的代码更改范围从微小到可怕。
2. 将数据库合并在一起。拥有许多没有物理原因的数据库是一种反模式。数据库不是应用程序模块化的逻辑单元。通过模式或表名前缀进行文档模块化。数据库是物理部署单元。

第三种方法：在 VM 中运行 SQL Server。

Answer 2

通过使用另一个答案发布的信息，我想出了一个似乎可行的解决方案。诚然，它看起来不像跨数据库连接那样高效或简洁，但它可以完成工作。

using (var context = new CustomerContext(CustomerID))
using (var e = new eContext())
{
    var globalUserList = e.GlobalLoginCustomerBridges
        .Join(e.GlobalLogins,
            glcb => glcb.glcbr_gl_id,
            gl => gl.gl_id,
            (glcb, gl) => new { glcb, gl })
        .Where(n => n.glcb.glcbr_customer_id == CustomerID)
        .Select(n => new User2
        {
            ID = (int)n.glcb.glcbr_user_id,
            GlobalLogin = n.gl.gl_login_name,
            GUID = n.gl.gl_GUID
        }).ToList();

    var customer = e.Customers
        .Join(e.DatabaseConnectionStrings,
        c => c.DatabaseConnectionID,
        d => d.DatabaseConnectionID,
        (c, d) => new { c, d })
        .Select(n => new Customer2
        {
            ID = n.c.CustomerID,
            Name = n.c.CustomerName,
            DatabaseConnectionName = n.d.DatabaseConnectionName,
            DatabaseConnectionString = n.d.DatabaseConnectionString1,
            GUID = n.c.cust_guid,
        }).ToList().FirstOrDefault(n => n.ID == CustomerID);

    var orgs = context.Organizations
        .Select(o => new Organization2
        {
            ID = o.org_id,
            Name = o.org_name,
        }).ToList();

    var users = context.Users
        .Select(n => new User2
        {
            ID = n.UserID,
            FirstName = n.UserFirstName,
        }).ToList();

    var userList = users
        .Join(globalUserList,
            u => u.ID,
            gl => gl.ID,
            (u, gl) => new { u, gl })
        .Join(context.OrganizationObjectBridges,
            u => u.u.ID,
            oob => oob.oob_object_id,
            (u, oob) => new { u, oob })
            .Where(o => o.oob.oob_object_type_id == 9)
        .Select(n => new User2
        {
            ID = n.u.u.ID,
            GlobalLogin = n.u.gl.GlobalLogin,
            FirstName = n.u.u.FirstName,
            GUID = n.u.gl.GUID,
            Customer = customer,
            Organization = orgs.FirstOrDefault(o => o.ID == n.oob.oob_org_id)
        }).Where(n => !isDisabled != null && n.Disabled == isDisabled).ToList();

    return userList;
}