ALTER VIEW 从​​视图中删除索引

Question

正如标题行所暗示的那样：在具有索引的 VIEW 上使用 ALTER VIEW 语句将在没有警告的情况下从 VIEW 中删除此（所有？）索引。我希望 ALTER VIEW 语句失败，通知我先删除索引。

SQL SERVER 中是否有更改此行为的设置？还是在 SQL 2012 (SP3) 之后的版本中发生了变化？

Answer 1

没有更改此行为的设置，在较新的 SQL Server 版本中也没有更改。SQL Server 2019 和 Azure SQL 数据库的当前文档备注部分的摘录：

ALTER VIEW 可以应用于索引视图；但是，ALTER VIEW 会无条件地删除视图上的所有索引

Answer 2

您可以防止使用 DDL 触发器更改索引视图。但是实现有点复杂，因为DDL触发器是在视图被修改和索引被删除之后运行的，但是在提交修改之前，你不能直接检测到视图之前有索引。

因此，您必须使用扩展属性进行一些恶作剧，只要在视图上创建索引，就将扩展属性放置在视图上。

例如：

create or alter trigger ddl_trig_prevent_alter_indexed_view   
on database  
for drop_index, create_index, alter_view
as   
begin
    --select eventdata().value('(/EVENT_INSTANCE/TSQLCommand/CommandText)[1]','nvarchar(max)')  , eventdata()

    declare @schemaName sysname, @objectName sysname, @eventType varchar(50), @targetObjectType varchar(50)
           ,@targetObjectName sysname, @targetObjectSchemaName sysname

    declare @e xml = eventdata();

    select @eventType = @e.value('(/EVENT_INSTANCE/EventType)[1]','varchar(50)'),
           @targetObjectType = @e.value('(/EVENT_INSTANCE/TargetObjectType)[1]','varchar(50)'),
           @targetObjectName = @e.value('(/EVENT_INSTANCE/TargetObjectName)[1]','sysname'),
           @schemaName = @e.value('(/EVENT_INSTANCE/SchemaName)[1]','sysname'),
           @objectName = @e.value('(/EVENT_INSTANCE/ObjectName)[1]','sysname')

    if @eventType = 'DROP_INDEX' and @targetObjectType = 'VIEW'
    begin
        --print @eventType
        set @targetObjectSchemaName = (select schema_name(schema_id) from sys.views where name = @targetObjectName)
        if exists( select * from fn_listextendedproperty ('HasIndex', 'SCHEMA', @targetObjectSchemaName, 'VIEW', @targetObjectName, NULL, NULL) )
           and not exists( select * from sys.indexes where object_id = object_id( concat(quotename(@targetObjectSchemaName),'.',quotename(@targetObjectName))) )
        begin
            exec sp_dropextendedproperty
                 @name = N'HasIndex' 
                ,@level0type = N'Schema', @level0name = @targetObjectSchemaName
                ,@level1type = N'View', @level1name = @targetObjectName
            print 'Extended property HasIndex on view dropped.'
        end

    end
    else if @eventType = 'CREATE_INDEX' and @targetObjectType = 'VIEW'
    begin
        --print @eventType
        set @targetObjectSchemaName = (select schema_name(schema_id) from sys.views where name = @targetObjectName)
        if exists( select * from fn_listextendedproperty ('HasIndex', 'SCHEMA', @targetObjectSchemaName, 'VIEW', @targetObjectName, NULL, NULL) )
        begin
            exec sp_updateextendedproperty  
                 @name = N'HasIndex' 
                ,@value = N'1' 
                ,@level0type = N'Schema', @level0name = @targetObjectSchemaName
                ,@level1type = N'View', @level1name = @targetObjectName
           print 'Extended property HasIndex on view updated.'
        end
        else
        begin
            exec sp_addextendedproperty  
                 @name = N'HasIndex' 
                ,@value = N'1' 
                ,@level0type = N'Schema', @level0name = @targetObjectSchemaName
                ,@level1type = N'View', @level1name = @targetObjectName
           print 'Extended property HasIndex on view added.'
        end

    end
    else if @eventType = 'ALTER_VIEW'
    begin
      --print @eventType
      if exists( select * from fn_listextendedproperty ('HasIndex', 'SCHEMA', @schemaName, 'VIEW', @objectName, NULL, NULL) where value = '1' )
      begin
         ;throw 50001,'Cannot alter view with an index.  Drop the index first.', 1;
         rollback;
         return;
      end
    end
    else
    begin 
      ;throw 50001,'Unexpected event type in ddl trigger.', 1
    end
end