什麼是可以使外鍵變爲不可信的一些場景

Question

我有一個OLTP和一個OLAP數據庫，我們在OLAP中保持一個滾動的13個月的數據。幾個ETL作業使得夜間作業保持最新狀態，並且在執行ETL時，沒有任何作業會禁用外鍵。偶爾，由於我還沒有發現的原因，我的一些OLTP外鍵變得不可信。我使用下面的腳本（感謝Brent Ozar的小組）來識別並修復這些鍵。

我的問題是：除了手動禁用然後忘記重新啓用密鑰，什麼情況會導致外鍵變得不可信？我已經搜遍了我們的ETL工作，沒有什麼突破。

腳本識別，然後修復不可信鍵：

識別不可信的鑰匙

下面的腳本，布倫特奧扎爾組的讚揚，將有助於識別不可信鍵。請注意，此腳本必須在連接到您希望檢查的給定數據庫時運行。

SELECT '[' + s.name + '].[' + o.name + '].[' + i.name + ']' AS keyname 
from sys.foreign_keys i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 

SELECT '[' + s.name + '].[' + o.name + '].[' + i.name + ']' AS keyname 
from sys.check_constraints i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 AND i.is_disabled = 0 

修復不可信鍵

一旦你已經確定不信任的鑰匙，使用下面的腳本來重新啓用它們：

WITH CHECK CHECK約束ALTER TABLE MyTableName MyConstraintName

大表需要時間，所以這應該在維護窗口期間執行。由於鍵被禁用，您可能會發現不符合約束規則的鍵值。這些值需要被編輯或刪除行以成功重新啓用密鑰。

ALTER TABLE腳本用於PriceGuide和PriceGuideDW

我已經做了一些修改，以布倫特奧扎爾腳本專門爲我們的數據庫。這些腳本會生成必要的ALTER TABLE腳本來修復不可信鍵：

Use PriceGuide 
Go 
SELECT 'ALTER TABLE [' + o.name + '] WITH CHECK CHECK CONSTRAINT ' + 
--'[' + s.name + '].[' + o.name + ']. 
+ '[' + i.name + '];' AS keyname 
from sys.foreign_keys i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 

SELECT 'ALTER TABLE [' + o.name + '] WITH CHECK CHECK CONSTRAINT ' + 
--'[' + s.name + '].[' + o.name + ']. 
+ '[' + i.name + '];' AS keyname 
from sys.check_constraints i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 AND i.is_disabled = 0 

Use PriceGuideDW 
Go 
SELECT 'ALTER TABLE [' + o.name + '] WITH CHECK CHECK CONSTRAINT ' + 
--'[' + s.name + '].[' + o.name + ']. 
+ '[' + i.name + '];' AS keyname 
from sys.foreign_keys i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 

SELECT 'ALTER TABLE [' + o.name + '] WITH CHECK CHECK CONSTRAINT ' + 
--'[' + s.name + '].[' + o.name + ']. 
+ '[' + i.name + '];' AS keyname 
from sys.check_constraints i 
INNER JOIN sys.objects o ON i.parent_object_id = o.object_id 
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id 
WHERE i.is_not_trusted = 1 AND i.is_not_for_replication = 0 AND i.is_disabled = 0