SQL Server查询过滤器的顺序很慢

Question

我已经为此苦苦挣扎了一段时间。

我有一个包含三个表的数据库（每个表都有数百万个记录），如下所示（为简单起见，删除了一些列：]]

1.[Entity]
    [Id]                UNIQUEIDENTIFIER PK,
    [EntityLevel_Id]    UNIQUEIDENTIFIER NOT NULL FK [EntityLevel] ([Id])
2.[EntityData]
    [Id]                UNIQUEIDENTIFIER PK,
    [Entity_Id]         UNIQUEIDENTIFIER NOT NULL FK [Entity] ([Id]),
    [DataLanguage_Id]   UNIQUEIDENTIFIER NOT NULL FK [Language] ([Id]),
    [Code]              NVARCHAR (250) NOT NULL
3.[EntityLevel]
    [Id]                UNIQUEIDENTIFIER PK,
    [Sort]              INT NOT NULL
存在索引如下

[IX_Entity_EntityLevelId] ON [Entity] ([EntityLevel_Id])
[IX_EntityData_EntityId] ON [EntityData] ([Entity_Id])
[IX_EntityData_DataLanguageId_Code] ON [EntityData] ([DataLanguage_Id], [Code])
[IX_EntityLevel_Sort] ON [EntityLevel] ([Sort])
为了消除由于选择的列而导致速度变慢的可能性，我仅选择一个固定值

以下查询运行非常快（不到1秒）：

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityData].[DataLanguage_Id] = 'B6930015-F177-4ED3-97B0-AAEF401F9265'
以下查询也非常快地运行：

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityData].[DataLanguage_Id] = 'B6930015-F177-4ED3-97B0-AAEF401F9265'
ORDER BY
    [EntityData].[Code] ASC
以下内容也可以快速运行：

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityLevel].[Sort] = 1
但是，以下查询运行非常缓慢（大约10秒）：

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityData].[DataLanguage_Id] = 'B6930015-F177-4ED3-97B0-AAEF401F9265'
    AND
    [EntityLevel].[Sort] = 1
ORDER BY
    [EntityData].[Code]
我不知道原因，而且我找不到任何应用更多索引的方法，因此查询运行更快

感谢您的任何帮助！

编辑：

以下查询也可以快速运行：

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityData].[DataLanguage_Id] = 'B6930015-F177-4ED3-97B0-AAEF401F9265'
    AND
    [EntityLevel].[Sort] = 1
和

SELECT TOP 20
    1
FROM
    [Entity]
    INNER JOIN [EntityData] ON [Entity].[Id] = [EntityData].[Entity_Id]
    INNER JOIN [EntityLevel] ON [Entity].[EntityLevel_Id] = [EntityLevel].[Id]
WHERE
    [EntityLevel].[Sort] = 1
ORDER BY
    [EntityData].[Code]
该问题仅在order by和两个过滤器中出现

我已经为此苦苦挣扎了一段时间。我有一个包含三个表的数据库（每个表都有数百万个记录），如下所示（为简单起见，删除了一些列）：1. [Entity] [Id] ...

Answer 1

尝试使用索引

Answer 2

您的问题是关于此查询的：