更改 Memory-Optimized 表

2017-06-13

不支持对内存优化表执行 ALTER操作。这包括更改bucket_count、添加或删除索引以及添加或删除列等作。本主题提供有关如何更新内存优化表的指南。

更新 Memory-Optimized 表的定义

更新内存优化表的定义要求使用更新的表定义创建新表，将数据复制到新表，然后开始使用新表。除非表是只读的，否则这需要停止表上的工作负荷，以确保在执行数据复制时不会对表进行任何更改。

以下过程概述了更新表所需的步骤。在此示例中，更新添加索引。此过程保留表的名称，并需要进行两次数据复制操作：一次复制到临时表，一次复制到新表。更改索引的桶数量或添加或删除列，这些操作的执行方式相同。

停止桌面上的工作。
为表生成脚本，并将新索引添加到脚本。

为引用 T 及其权限的架构绑定对象（主要是本机编译的存储过程）生成脚本。

可以使用以下查询找到引用表的架构绑定对象：

declare @t nvarchar(255) = N'<table name>'  

select r.referencing_schema_name, r.referencing_entity_name  
from sys.dm_sql_referencing_entities (@t, 'OBJECT') as r join sys.sql_modules m on r.referencing_id=m.object_id  
where r.is_caller_dependent = 0 and m.is_schema_bound=1;

存储过程的权限可以使用以下 Transact-SQL 进行脚本编写：

declare @sp nvarchar(255) = N'<procedure name>'  
declare @permissions nvarchar(max) = N''  

select @permissions += dp.state_desc + N' ' + dp.permission_name + N' ON ' +   
   quotename(schema_name(o.schema_id)) + N'.' + quotename(o.name) + N' TO ' +  
   quotename(u.name) + N'; ' + char(13)  
from sys.database_permissions as dp  

join sys.database_principals as u  
   on u.principal_id = dp.grantee_principal_id  

join sys.objects as o  
   on o.object_id = dp.major_id  
where dp.class = 1 /* object */  
   and dp.minor_id = 0 and o.object_id=object_id(@sp);  

select @permissions

创建表的副本，并将原始表中的数据复制到表的副本。可以使用以下 Transact-SQL¹ 创建副本。
```
select * into dbo.T_copy from dbo.T  
```
如果有足够的可用内存，T_copy 可以是一个内存优化表，这样数据复制会更快。²
删除引用原始表的架构绑定对象。
删除原始表。
使用包含新索引的脚本创建新表（T）。
将数据从 T_copy 中复制到 T。
重新创建引用架构绑定的对象并应用权限。
启动T上的工作负荷。

¹ 请注意， T_copy 此示例中保存到磁盘。如果备份 T 可用， T_copy 可以是临时表或非持久表。

² 必须有足够的内存。T_copy 内存不会在DROP TABLE上立即释放。如果 T_copy 内存已优化，则需要有足够的内存用于另外两个副本 T。如果 T_copy 是基于磁盘的表，则只需有足够的内存来额外创建一个 T 的副本，因为垃圾回收器在删除 T 的旧版本后需要赶上。

更改架构（PowerShell）

以下 PowerShell 脚本通过编写表和关联权限的脚本来准备和生成架构更改。

prepare_schema_change.ps1 <serverName> <databaseName> <schemaName> <tableName>

此脚本采用表的参数，并编写对象及其权限，并引用当前文件夹中的架构绑定对象及其权限。共生成 7 个脚本，用于更新输入表的架构：

将数据复制到临时表（堆）。
删除引用表的架构绑定对象。
删除表。
使用新架构重新创建表并重新应用权限。
将数据从临时表复制到重新创建的表。
重新创建引用表及其权限的架构绑定对象。
删除临时表。

应更新步骤 4 的脚本，以反映所需的架构更改。如果表的列有任何更改，应根据需要更新步骤 5（从临时表复制数据）和 6（重新创建存储过程）的脚本。

# Prepare for schema changes by scripting out the table, as well as associated permissions
# Usage: prepare_schema_change.ps1 server_name db_name schema_name table_name  
# stop execution once an error occurs  
$ErrorActionPreference="Stop"  
  
if($args.Count -le 3)  
{  
   throw "Usage prepare_schema_change.ps1 server_name db_name schema_name table_name"  
}  
  
$servername = $args[0]  
$database = $args[1]  
$schema = $args[2]  
$object = $args[3]  
  
$object_heap = "$object$(Get-Random)"  
  
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SMO") | Out-Null  
  
$server =  New-Object ("Microsoft.SqlServer.Management.SMO.Server") ($servername)  
$scripter = New-Object ("Microsoft.SqlServer.Management.SMO.Scripter") ($server)  
  
## initialize table variable  
$tableUrn = $server.Databases[$database].Tables[$object, $schema]  
if($tableUrn.Count -eq 0)  
{  
   throw "Table or database not found"  
}  
  
## initialize scripting object  
$scriptingOptions = New-Object ("Microsoft.SqlServer.Management.SMO.ScriptingOptions")
$scriptingOptions.Permissions = $True  
$scriptingOptions.ScriptDrops = $True  
  
$scripter.Options = $scriptingOptions;  
  
Write-Host "(1) Scripting SELECT INTO $object_heap for table [$object] to 1_copy_to_heap_for_$schema`_$object.sql"  
Echo "SELECT * INTO $schema.$object_heap FROM $schema.$object WITH (SNAPSHOT)" | Out-File "1_copy_to_heap_$schema`_$object.sql";  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(2) Scripting DROP for procs schema-bound to [$object] 2_drop_procs_$schema`_$object.sql"  
## query referencing schema-bound objects  
$dt = $server.Databases[$database].ExecuteWithResults("select r.referencing_schema_name, r.referencing_entity_name  
from sys.dm_sql_referencing_entities ('$schema.$object', 'OBJECT') as r join sys.sql_modules m on r.referencing_id=m.object_id  
where r.is_caller_dependent = 0 and m.is_schema_bound=1;")  
  
## initialize out file  
Echo "" | Out-File "2_drop_procs_$schema`_$object.sql"  
## loop through schema-bound objects  
ForEach ($t In $dt.Tables)  
{    
   ForEach ($r In $t.Rows)  
   {    
      ## script object   
      $so =  $server.Databases[$database].StoredProcedures[$r[1], $r[0]]  
      $scripter.Script($so) | Out-File -Append "2_drop_procs_$schema`_$object.sql"  
   }  
}  
Write-Host "--done--"  
Write-Host ""  
Write-Host "(3) Scripting DROP table for [$object] to 3_drop_table_$schema`_$object.sql"
$scripter.Script($tableUrn) | Out-File "3_drop_table_$schema`_$object.sql";
Write-Host "--done--"  
Write-Host ""  
  
## now script creates  
$scriptingOptions.ScriptDrops = $False  
  
Write-Host "(4) Scripting CREATE table and permissions for [$object] to !please_edit_4_create_table_$schema`_$object.sql"  
Write-Host "***** rename this script to 4_create_table.sql after completing the updates to the schema"
$scripter.Script($tableUrn) | Out-File "!please_edit_4_create_table_$schema`_$object.sql";  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(5) Scripting INSERT INTO table from heap and UPDATE STATISTICS for [$object] to 5_copy_from_heap_$schema`_$object.sql"  
Write-Host "[update this script if columns are added to or removed from the table]"  
Echo "INSERT INTO [$schema].[$object] SELECT * FROM [$schema].[$object_heap]; UPDATE STATISTICS [$schema].[$object] WITH FULLSCAN, NORECOMPUTE" | Out-File "5_copy_from_heap_$schema`_$object.sql";  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(6) Scripting CREATE PROC and permissions for procedures schema-bound to [$object] to 6_create_procs_$schema`_$object.sql"  
Write-Host "[update the procedure definitions if columns are renamed or removed]"  
## initialize out file  
Echo "" | Out-File "6_create_procs_$schema`_$object.sql"  
## loop through schema-bound objects  
ForEach ($t In $dt.Tables)  
{    
   ForEach ($r In $t.Rows)  
   {    
      ## script the schema-bound object  
      $so =  $server.Databases[$database].StoredProcedures[$r[1], $r[0]]  
      ForEach($s In $scripter.Script($so))  
        {  
            Echo $s | Out-File -Append "6_create_procs_$schema`_$object.sql"  
            Echo "GO" | Out-File -Append "6_create_procs_$schema`_$object.sql"  
        }  
   }  
}  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(7) Scripting DROP $object_heap to 7_drop_heap_$schema`_$object.sql"  
Echo "DROP TABLE $schema.$object_heap" | Out-File "7_drop_heap_$schema`_$object.sql";  
Write-Host "--done--"  
Write-Host ""

以下 PowerShell 脚本执行上一示例中脚本的架构更改。此脚本采用表作为参数，并执行为该表和关联的存储过程生成的架构更改脚本。

使用情况：execute_schema_change.ps1 server_name**db_nameschema_nametable_name

# stop execution once an error occurs  
$ErrorActionPreference="Stop"  
  
if($args.Count -le 3)  
{  
   throw "Usage execute_schema_change.ps1 server_name db_name schema_name table_name"  
}  
  
$servername = $args[0]  
$database = $args[1]  
$schema = $args[2]  
$object = $args[3]  
  
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SMO") | Out-Null  
  
$server =  New-Object ("Microsoft.SqlServer.Management.SMO.Server") ($servername)  
$database = $server.Databases[$database]  
$table = $database.Tables[$object, $schema]  
if($table.Count -eq 0)  
{  
   throw "Table or database not found"  
}  
  
$1 = Get-Item "1_copy_to_heap_$schema`_$object.sql"  
$2 = Get-Item "2_drop_procs_$schema`_$object.sql"  
$3 = Get-Item "3_drop_table_$schema`_$object.sql"  
$4 = Get-Item "4_create_table_$schema`_$object.sql"  
$5 = Get-Item "5_copy_from_heap_$schema`_$object.sql"  
$6 = Get-Item "6_create_procs_$schema`_$object.sql"  
$7 = Get-Item "7_drop_heap_$schema`_$object.sql"  
  
Write-Host "(1) Running SELECT INTO heap for table [$object] from 1_copy_to_heap_for_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $1.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(2) Running DROP for procs schema-bound from [$object] 2_drop_procs_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $2.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(3) Running DROP table for [$object] to 4_drop_table_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $3.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(4) Running CREATE table and permissions for [$object] from 4_create_table_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $4.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(5) Running INSERT INTO table from heap for [$object] and UPDATE STATISTICS from 5_copy_from_heap_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $5.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(6) Running CREATE PROC and permissions for procedures schema-bound to [$object] from 6_create_procs_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $6.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""  
  
Write-Host "(7) Running DROP heap from 7_drop_heap_$schema`_$object.sql"  
$database.ExecuteNonQuery("$(Echo $7.OpenText().ReadToEnd())")  
Write-Host "--done--"  
Write-Host ""

另请参阅

Memory-Optimized 表

通过

更改 Memory-Optimized 表

更新 Memory-Optimized 表的定义

更改架构 （PowerShell）

另请参阅

其他资源

更改架构（PowerShell）