【推荐】[SQL优化工具]Quest.Central.For.Databases——SQL Tuning for SQL Server

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　　随着企业数据库的急剧膨胀和日益复杂，DBA为保证数据库性能所付出的努力与日俱增，手工或使用多种无法集成的管理工具，都会给日常管理和维护带来不必要的困难。 Quest Central for Databases 是一种集成化、图形化、跨平台的数据库管理解决方案，可以管理异构环境下的 Oracle、DB2 和 SQL server 数据库。Quest Central for Databases 消除了企业IT人员管理多种数据库时面临的技术障碍，提高了IT人员工作效率，改善了数据库性能和数据库应用的可用性。为灵活满足用户的不同需求，Quest Central for Databases 采用了模块化产品架构。
　　该产品包括下列功能模块:
　　1.         数据库管理（DBA）
　　2.         数据库监控（Monitoring Pack）
　　3.         数据库诊断 (Spotlight Diagnostics)
　　4.         数据库分析 (Database Analysis)
　　5.         SQL优化 (SQL Tuning)
　　6.         空间管理 (Space Management)
　　7.         压力测试 (Load Generator)
　　8.         数据生成 (Data Generator)
　　9.         PL/SQL 开发 (TOAD)
　　10.     专家建议 (Knowledge Expert)
　　今天主要介绍其中的SQL优化工具—— SQL Tuning for SQL Server
　　一、SQL Tuning for SQL Server简介
　　SQL语句的优化对发挥数据库的最佳性能非常关键。然而不幸的是，应用优化通常由于时间和资源的因素而被忽略。SQL Tuning (SQL优化)模块可以对比和评测特定应用中SQL语句的运行性能，提出智能化的优化建议，帮助用户改善应用的响应时间。SQL优化模块具有非介入式SQL采集、自动优化和专家建议等功能，全面改善SQL优化工作。
　　       二、SQL Tuning for SQL Server的使用
　　1、打开Quest Database Management Solutions弹出窗口如图1所示       
      
                                                                          图1   
　　2、在红色标记处打开SQL Tuning 优化SQL     
　　（1）建立连接。
　　    在Quest Central主界面上的“Database”树上选择“SQL Server”，然后在下方出现的“Tools”框中选择“SQL Tuning”选项，打开“Lanch SQL Tuning for SQL Server Connections”对话框（图2、图3）。我们在这里建立数据库服务器的连接，以后的分析工作都会在它上面完成。
　　                    
                                         图2 “建立连接”对话框
　　                            
                                         图3
　　     双击“New Connection”图标，在弹出窗口中输入数据库的信息，单击“OK”，然后单击“Connect”即可。
　　（2）分析原始SQL语句 ，在单击“Connect”后将弹出一个新窗口，如图4
　　              
                                                                  图4
　　在打开窗口的“Oriangal SQL”文本框内输入需要分析的原始SQL语句，红色标记处选择对应的数据库名，SQL语句代码如下：   
　　

原始SQL语句

SELECT dbo.Person_BasicInfo.*, dbo.Graduater_GraduaterRegist.RegistNO AS RegistNO,
      dbo.Graduater_GraduaterRegist.RegistTime AS BaoDaoTime,
      dbo.Graduater_GraduaterRegist.RegistMan AS RegistMan,
      dbo.Graduater_Business.ComeFrom AS ComeFrom,
      dbo.Graduater_Business.Code AS Code, dbo.Graduater_Business.Status AS Status,
      dbo.Graduater_Business.ApproveResult AS ApproveResult,
      dbo.Graduater_Business.NewCorp AS NewCorp,
      dbo.Graduater_Business.CommendNumber AS CommendNumber,
      dbo.Graduater_Business.EmployStatus AS EmployStatus,
      dbo.Graduater_Business.NewCommendTime AS NewCommendTime,
      dbo.Graduater_Business.GetSource AS GetSource,
      dbo.Graduater_Business.EmployTime AS EmployTime,
      dbo.Graduater_Business.Job AS Job, dbo.Graduater_Business.FillMan AS FillMan,
      dbo.Graduater_Business.FillTime AS FillTime,
      dbo.Graduater_Business.IsCommendOK AS IsCommendOK,
      dbo.Graduater_Business.ApproveUser AS ApproveUser,
      dbo.Graduater_Business.ApproveTime AS ApproveTime,
      dbo.Graduater_Business.RegistTime AS RegistTime,
      dbo.Graduater_Business.EmployCorp AS EmployCorp,
      dbo.Graduater_Business.JobRemark AS JobRemark,
      CASE WHEN dbo.Graduater_Business.ComeFrom = 'WS' THEN '网上登记' WHEN dbo.Graduater_Business.ComeFrom
       = 'HP' THEN '华普大厦' WHEN dbo.Graduater_Business.ComeFrom = 'JD' THEN '精典大厦'
       WHEN dbo.Graduater_Business.ComeFrom = 'MC' THEN '赛马场' WHEN ComeFrom =
       'ZX' THEN '高指中心' END AS ComeFromName,
      dbo.Person_Contact.Address AS Address, dbo.Person_Contact.Zip AS Zip,
      dbo.Person_Contact.Telephone AS Telephone, dbo.Person_Contact.Mobile AS Mobile,
      dbo.Person_Contact.Email AS Email, dbo.Person_Contact.IM AS IM,
      dbo.Person_Skill.ForeignLanguage AS ForeignLanguage,
      dbo.Person_Skill.ForeignLanguageLevel AS ForeignLanguageLevel,
      dbo.Person_Skill.CantoneseLevel AS CantoneseLevel,
      dbo.Person_Skill.MandarinLevel AS MandarinLevel,
      dbo.Person_Skill.Language AS Language,
      dbo.Person_Skill.TechnicalTitle AS TechnicalTitle,
      dbo.Person_Skill.ComputerLevel AS ComputerLevel,
      dbo.Person_EmployPurpose.JobType AS JobType,
      dbo.Person_EmployPurpose.Vocation AS Vocation,
      dbo.Person_EmployPurpose.JobPlace AS JobPlace,
      dbo.Person_EmployPurpose.Salary AS Salary,
      dbo.Person_EmployPurpose.OnJobDate AS OnJobDate,
      dbo.Person_EmployPurpose.CorpType AS CorpType,
      dbo.Person_EmployPurpose.Job AS RequireJob, YEAR(GETDATE())
      - YEAR(dbo.Person_BasicInfo.Birthday) AS Age,
      dbo.Graduater_Business.EmployType AS EmployType,
      dbo.Graduater_Business.EmployTypeCode AS EmployTypeCode,
      dbo.Graduater_Business.EmployCorpType AS EmployCorpType,
      CASE WHEN dbo.Graduater_Business.PrintStatus = '已打印' THEN '已打印' ELSE '未打印'
       END AS PrintStatus, dbo.Graduater_Business.PrintTime AS PrintTime,
      CASE WHEN dbo.Graduater_Business.EmployStatus = '是' THEN '已就业' ELSE '未就业'
       END AS EmployStatusView
FROM dbo.Person_BasicInfo INNER JOIN
      dbo.Graduater_Business ON
      dbo.Person_BasicInfo.PersonID = dbo.Graduater_Business.PersonID LEFT OUTER JOIN
      dbo.Graduater_GraduaterRegist ON
      dbo.Graduater_Business.GradBusinessID = dbo.Graduater_GraduaterRegist.GraduaterGUID
       INNER JOIN
      dbo.Person_Contact ON
      dbo.Person_BasicInfo.PersonID = dbo.Person_Contact.PersonID INNER JOIN
      dbo.Person_Skill ON
      dbo.Person_BasicInfo.PersonID = dbo.Person_Skill.PersonID INNER JOIN
      dbo.Person_EmployPurpose ON
      dbo.Person_BasicInfo.PersonID = dbo.Person_EmployPurpose.PersonID　　然后点击工具栏上的“Execute”按钮，执行原始的SQL语句，SQL Tuning会自动分析SQL的执行计划，并把分析结果显示到界面上（图5）。                     
                       
　　　　　　　　　　　　　　　　　　　　　　图5 分析原始SQL语句
　　   （3）优化SQL。
　　   现在我们点击工具栏上的“Optimize Statement”按钮,让SQL Tuning开始优化SQL，完成后，可以看到SQL Tuning产生了19条与原始SQL等价的优化方案（图6）。
　　          
                                                        图6 SQL优化方案
　　 （4）获得最优SQL。
　　     接下来，我们来执行上面产生的优化方案，以选出性能最佳的等效SQL语句。在列表中选择需要执行的优化方案(默认已全部选中)，然后点击工具栏上的“Execute”按钮旁边的下拉菜单，选择“Execute Selected”。等到所有SQL运行完成后,点击界面左方的“Tuning Resolution”按钮，
可以看到最优的SQL已经出来啦，运行时间竟然可以提高21%！（图7）
　　          
                                            图7 “Tuning Resolution”界面
　　     最优的SQL语句如下：  
　　

优化后的SQL语句

SELECT dbo.Person_BasicInfo.*,
       dbo.Graduater_GraduaterRegist.RegistNO AS RegistNO,
       dbo.Graduater_GraduaterRegist.RegistTime AS BaoDaoTime,
       dbo.Graduater_GraduaterRegist.RegistMan AS RegistMan,
       dbo.Graduater_Business.ComeFrom AS ComeFrom,
       dbo.Graduater_Business.Code AS Code,
       dbo.Graduater_Business.Status AS Status,
       dbo.Graduater_Business.ApproveResult AS ApproveResult,
       dbo.Graduater_Business.NewCorp AS NewCorp,
       dbo.Graduater_Business.CommendNumber AS CommendNumber,
       dbo.Graduater_Business.EmployStatus AS EmployStatus,
       dbo.Graduater_Business.NewCommendTime AS NewCommendTime,
       dbo.Graduater_Business.GetSource AS GetSource,
       dbo.Graduater_Business.EmployTime AS EmployTime,
       dbo.Graduater_Business.Job AS Job,
       dbo.Graduater_Business.FillMan AS FillMan,
       dbo.Graduater_Business.FillTime AS FillTime,
       dbo.Graduater_Business.IsCommendOK AS IsCommendOK,
       dbo.Graduater_Business.ApproveUser AS ApproveUser,
       dbo.Graduater_Business.ApproveTime AS ApproveTime,
       dbo.Graduater_Business.RegistTime AS RegistTime,
       dbo.Graduater_Business.EmployCorp AS EmployCorp,
       dbo.Graduater_Business.JobRemark AS JobRemark,
       CASE WHEN dbo.Graduater_Business.ComeFrom = 'WS' THEN '网上登记'
            WHEN dbo.Graduater_Business.ComeFrom = 'HP' THEN '华普大厦'
            WHEN dbo.Graduater_Business.ComeFrom = 'JD' THEN '精典大厦'
            WHEN dbo.Graduater_Business.ComeFrom = 'MC' THEN '赛马场'
            WHEN ComeFrom = 'ZX' THEN '高指中心' END AS ComeFromName,
       dbo.Person_Contact.Address AS Address,
       dbo.Person_Contact.Zip AS Zip,
       dbo.Person_Contact.Telephone AS Telephone,
       dbo.Person_Contact.Mobile AS Mobile,
       dbo.Person_Contact.Email AS Email,
       dbo.Person_Contact.IM AS IM,
       dbo.Person_Skill.ForeignLanguage AS ForeignLanguage,
       dbo.Person_Skill.ForeignLanguageLevel AS ForeignLanguageLevel,
       dbo.Person_Skill.CantoneseLevel AS CantoneseLevel,
       dbo.Person_Skill.MandarinLevel AS MandarinLevel,
       dbo.Person_Skill.Language AS Language,
       dbo.Person_Skill.TechnicalTitle AS TechnicalTitle,
       dbo.Person_Skill.ComputerLevel AS ComputerLevel,
       dbo.Person_EmployPurpose.JobType AS JobType,
       dbo.Person_EmployPurpose.Vocation AS Vocation,
       dbo.Person_EmployPurpose.JobPlace AS JobPlace,
       dbo.Person_EmployPurpose.Salary AS Salary,
       dbo.Person_EmployPurpose.OnJobDate AS OnJobDate,
       dbo.Person_EmployPurpose.CorpType AS CorpType,
       dbo.Person_EmployPurpose.Job AS RequireJob,
       YEAR(GETDATE()) - YEAR(dbo.Person_BasicInfo.Birthday) AS Age,
       dbo.Graduater_Business.EmployType AS EmployType,
       dbo.Graduater_Business.EmployTypeCode AS EmployTypeCode,
       dbo.Graduater_Business.EmployCorpType AS EmployCorpType,
       CASE WHEN dbo.Graduater_Business.PrintStatus = '已打印' THEN '已打印'
            ELSE '未打印' END AS PrintStatus,
       dbo.Graduater_Business.PrintTime AS PrintTime,
       CASE WHEN dbo.Graduater_Business.EmployStatus = '是' THEN '已就业'
            ELSE '未就业' END AS EmployStatusView
  FROM dbo.Person_BasicInfo
       INNER JOIN dbo.Graduater_Business
          ON dbo.Person_BasicInfo.PersonID = dbo.Graduater_Business.PersonID
       LEFT OUTER JOIN dbo.Graduater_GraduaterRegist
         ON dbo.Graduater_Business.GradBusinessID = dbo.Graduater_GraduaterRegist.GraduaterGUID
       INNER JOIN dbo.Person_Contact
          ON dbo.Person_BasicInfo.PersonID = dbo.Person_Contact.PersonID
       INNER JOIN dbo.Person_Skill
          ON dbo.Person_BasicInfo.PersonID = dbo.Person_Skill.PersonID
       INNER JOIN dbo.Person_EmployPurpose
          ON dbo.Person_BasicInfo.PersonID = dbo.Person_EmployPurpose.PersonID
OPTION (FORCE ORDER)　　
　　（5）学习书写专家级的SQL语句 。
　　    通过上面的步骤，我们已经可以实现自动优化SQL语句，但更重要的是，我们还可以学习如何书写这样高性能的SQL语句。点击界面左方的“Compare Scenarios”按钮，我们可以比较优化方案和原始SQL中的任意2条SQL语句，SQL Tuning会将它们之间的不同之处以不同颜色表示出来，
还可以在下方的“执行计划”中，通过比较两条SQL语句的执行计划的不同，来了解其中的差异（图8）。
　　            
                                      图8 “Compare Scenarios”界面
　　   三、总结
　　    SQL Tuning等人工智能自动SQL优化工具的出现，为我们节省出大量的时间和精力。借助这些工具的帮助，书写专家级的SQL语句将不再是难事。
   Quest.Central.For.Databases下载地址：
   http://58.251.57.206/down?cid=1669258673&t=14&fmt=&usrinput=Quest.Central&dt=0&ps=0_0&rt=0kbs&plt=0&spd=9
   SQL Tuning操作手册英文版:
　　   http://files.iyunv.com/dreamof/SQL.Tuning.rar
　　
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