表值函数xml阅读器在SQL Server中引起性能

Question

您能否帮我改变脚本字符串或其他任何改进查询的方法。

如果您可以从以下脚本提供示例脚本，我不是开发人员。表值函数在查询的实际执行计划中花费49％并运行7分钟。

提前谢谢。

LEFT OUTER JOIN 
  (SELECT  
       pp2.patient_id,
       Foodallergy= STUFF((SELECT ',' + cd.description 
                           FROM [OHCP_OHProblemList].[problemlist].[problems_v] pp 
                           INNER JOIN [OHCP_OHCLINICAL].[CodeSet].[CodeSet] CS ON cs.identifier = pp.problem_name_code_set
                           INNER JOIN ohcp_ohclinical.codeset.CodeDefinition cd ON (cd.code = pp.problem_name_code AND cd.codesetid = cs.id) 
                           WHERE patient_id = pp2.patient_id 
                             AND pp.last_update_action NOT IN ('DELETE', 'CLOSE') 
                             AND pp.adr_class_code IN (3,4)
                             AND cd.description != 'Other'
                           ORDER BY [description] 
                           FOR XML PATH ('')), 1, 1, ''),
       description = STUFF((SELECT N',' + ' Other:'  + pp.problem_name_freetext_desc
                            FROM [OHCP_OHProblemList].[problemlist].[problems_v] pp 
                            INNER JOIN [OHCP_OHCLINICAL].[CodeSet].[CodeSet] CS on cs.identifier = pp.problem_name_code_set
                            INNER JOIN ohcp_ohclinical.codeset.CodeDefinition cd ON (cd.code = pp.problem_name_code AND cd.codesetid = cs.id)
                            WHERE patient_id = pp2.patient_id 
                              AND pp.last_update_action not in ('DELETE', 'CLOSE') 
                              AND pp.adr_class_code in (3, 4)  
                            FOR XML PATH('')), 1, 1, '') 
  FROM 
      [OHCP_OHProblemList].[problemlist].[problems_v] pp2  
  GROUP BY 
      pp2.patient_id) AS problem ON problem.patient_id = externalpatientid.externalpatientid