Azure上的SQL遞歸CTE超時

Question

我有以下視圖，它在Azure上運行時存在嚴重的性能問題。如果我在本地複製Azure數據庫並在視圖上運行任何查詢，它會在幾秒鐘內返回。對視圖的同一查詢在Azure上超時。

爲什麼針對視圖的查詢會在Azure上超時？

  CREATE VIEW [dbo].[JobTypeDescendantJobTypes] 
      AS 
      WITH cte (ParentJobTypeId, Id) 
         AS (SELECT Id , 
            Id 
          FROM  dbo.JobTypes 
          UNION ALL 
          SELECT e.Id , 
            cte.Id 
          FROM  cte 
            INNER JOIN dbo.JobTypes AS e ON e.ParentJobTypeId = cte.ParentJobTypeId 
         ) 
      SELECT ISNULL(Id, 0) AS ParentJobTypeId, 
        ISNULL(ParentJobTypeId, 0) AS Id 
      FROM cte 

Answer 1

重建您的統計/索引。要做到這一點

的一種方法是：（*注意：在生產運行慎用）

DECLARE @table nvarchar(255) 
DECLARE tablecursor CURSOR FOR 
SELECT table_name FROM information_schema.tables WHERE table_type = 'base table' 

OPEN tablecursor 
FETCH NEXT FROM tablecursor INTO @table 

WHILE @@FETCH_STATUS = 0 
BEGIN 
    exec('ALTER INDEX ALL ON ' + @table + ' REBUILD') 
    FETCH NEXT FROM tablecursor INTO @table 
END 

CLOSE tablecursor 
DEALLOCATE tablecursor