Question

我是SQL的新手，我在SQL query的表现方面遇到了一些问题。我按照谷歌的一些观点创建了所需的indexes。但仍然无法改善表现。

指导我提高遵循query的效果。 tables有数百万条记录。

SELECT TOP 15 id, 
              field1, 
              field2 
FROM   (SELECT DISTINCT 0               AS ID, 
                        tblsuites.suite Field1, 
                        'Work Order'    AS Field2 
        FROM   tbljb_schedules 
               INNER JOIN tblsuites 
                       ON tbljb_schedules.tblsuites_id = tblsuites.tblsuites_id 
               INNER JOIN tblsites 
                       ON tbljb_schedules.tblsites_id = tblsites.tblsites_id 
               LEFT OUTER JOIN tblbldgs 
                            ON 
               tbljb_schedules.tblbldgs_id = tblbldgs.tblbldgs_id 
        WHERE  tbljb_schedules.tbldomains_id = 28 
               AND tbljb_schedules.internalonly = 0 
               AND tbljb_schedules.tblsites_id IN (SELECT tblsites_id 
                                                   FROM   tbllogins_sites 
                                                   WHERE  tbllogins_id = 264 
                                                          AND 
                                                  tblsites.active = 1) 
               AND ( tblsuites.suite LIKE '%1%' ) 
        UNION 
        SELECT DISTINCT 0               AS ID, 
                        tblsuites.suite Field1, 
                        'Work Order'    AS Field2 
        FROM   arcjb_schedules 
               INNER JOIN tblsuites 
                       ON arcjb_schedules.tblsuites_id = tblsuites.tblsuites_id 
               INNER JOIN tblsites 
                       ON arcjb_schedules.tblsites_id = tblsites.tblsites_id 
               LEFT OUTER JOIN tblbldgs 
                            ON arcjb_schedules.tblbldgs_id = 
                               tblbldgs. tblbldgs_id 
        WHERE  arcjb_schedules.tbldomains_id = 28 
               AND arcjb_schedules.internalonly = 0 
               AND arcjb_schedules.tblsites_id IN (SELECT tblsites_id 
                                                   FROM   tbllogins_sites 
                                                   WHERE  tbllogins_id = 264 
                                                          AND 
                                                  tblsites.active = 1) 
               AND ( tblsuites.suite LIKE '%1%' )) T 
ORDER  BY CASE 
            WHEN Charindex('1', field1) = 1 THEN 0 
            ELSE 1 
          END, 
          field1

Answer 1

也许您应该尝试以下代码更改

SELECT TOP 15 
id,
field1,
field2
FROM
(
    SELECT 
       0 AS ID,
       tblsuites.suite Field1,
       'Work Order' AS Field2,
       SeqOne = CASE WHEN CHARINDEX('1', tblsuites.suite)= 1
                THEN 1
             ELSE 0 END
       FROM tbljb_schedules
          INNER JOIN tblsuites 
             ON tbljb_schedules.tblsuites_id = tblsuites.tblsuites_id
          INNER JOIN tblsites 
             ON tbljb_schedules.tblsites_id = tblsites.tblsites_id
          LEFT OUTER JOIN tblbldgs 
             ON tbljb_schedules.tblbldgs_id = tblbldgs.tblbldgs_id
          WHERE tbljb_schedules.tbldomains_id = 28
             AND tbljb_schedules.internalonly = 0
             AND EXISTS  -- Replace IN With EXISTS
             (
             SELECT 
                1
                FROM tbllogins_sites
                WHERE tbllogins_id = 264
                AND tblsites.active = 1
                AND tblsites_id = tbljb_schedules.tblsites_id
             )
             AND (tblsuites.suite LIKE '%1%')

    UNION -- UNION Will By Default Take DISTINCT Records

    SELECT 
       0 AS ID,
       tblsuites.suite Field1,
       'Work Order' AS Field2,
       SeqOne = CASE WHEN CHARINDEX('1', tblsuites.suite)= 1
                THEN 1
             ELSE 0 END
       FROM arcjb_schedules
       INNER JOIN tblsuites ON arcjb_schedules.tblsuites_id = tblsuites.tblsuites_id
       INNER JOIN tblsites ON arcjb_schedules.tblsites_id = tblsites.tblsites_id
       LEFT OUTER JOIN tblbldgs ON arcjb_schedules.tblbldgs_id = tblbldgs.tblbldgs_id
       WHERE arcjb_schedules.tbldomains_id = 28
       AND arcjb_schedules.internalonly = 0
       AND EXISTS 
          (
             SELECT 
             1
                FROM tbllogins_sites
                    WHERE tbllogins_id = 264
                       AND tblsites.active = 1
                       AND tblsites_id = arcjb_schedules.tblsites_id
          )
       AND (tblsuites.suite LIKE '%1%')
)T
ORDER BY
    SeqOne,
    field1;

Answer 2

性能调优更像是一个反复试验的主题。

查看你的代码，我可以看到一个重要的性能罪犯。 where子句中的这个条件：和tblsuites.suite LIKE'％1％'

我不知道tblSuites表有多大，但使用LIKE'％1％'会使优化器执行表扫描而不是索引查找，所以即使你已经索引该列也没用。

也按照@Jayasurya Satheesh在答案中提到的那样。

需要提高SQL查询的性能

2 个答案: