Sql Oracle查询优化建议

下面的查询需要很长时间，下面的谓词只用于获取唯一的记录，因此我想知道是否有其他方法可以重写同一个查询而不多次调用下面的谓词来获取唯一的ID

select max(c.id) from plocation c where c.ids = y.ids and c.idc = y.idc)
select max(cr.id) from plocation_log cr where cr.ids = yt.ids and cr.idc = yt.idc)
select max(pr.id) from patentpr where pr.ids = p.ids and pr.idc = p.idc)           

我的完整示例查询

SELECT to_char(p.pid) AS patentid,
       p.name,
       x.dept,
       y.location
  FROM patent p
  JOIN pdetails x ON p.pid = x.pid  AND x.isactive = 1
  JOIN plocation y
            ON y.idr = p.idr
           AND y.idc = p.idc
           AND y.id = *(select max(c.id) from plocation c where c.ids = y.ids and c.idc = y.idc)*
           AND y.idopstype in (36, 37)
   JOIN plocation_log yt
            ON yt.idr = y.idr
           AND yt.idc= y.idc
           AND yt.id = *(select max(cr.id) from plocation_log cr where cr.ids = yt.ids and cr.idc = yt.idc)*
           AND yt.idopstype in (36,37)
WHERE
      p.idp IN (10,20,30)
   AND p.id = *(select max(pr.id) from patent pr where pr.ids = p.ids and pr.idc = p.idc)*
   AND p.idopstype in (36,37)

---

正如Impaler所评论的，一种选择是使用分析函数而不是相关子查询。其思想是使用

rank（）

对子查询中的记录进行排序，然后在外部查询中进行筛选（连接条件或

WHERE

子句）

考虑：

SELECT to_char(p.pid) AS patentid,
       p.name,
       x.dept,
       y.location
  FROM (SELECT p.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM patinet) p
  JOIN pdetails x ON p.pid = x.pid  AND x.isactive = 1
  JOIN (SELECT y.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM plocation y) y
            ON y.idr = p.idr
           AND y.idc = p.idc
           AND y.idopstype in (36, 37)
           AND y.rn = 1
   JOIN (SELECT y.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM plocation_log yt) yt
            ON yt.idr = y.idr
           AND yt.idc= y.idc
           AND yt.idopstype in (36,37)
           AND yt.rn = 1
WHERE
   p.idp IN (10,20,30)
   AND p.idopstype in (36,37)
   AND p.rn = 1
   

---

正如Impaler所评论的，一种选择是使用分析函数而不是相关子查询。其思想是使用

rank（）

对子查询中的记录进行排序，然后在外部查询中进行筛选（连接条件或

WHERE

子句）

考虑：

SELECT to_char(p.pid) AS patentid,
       p.name,
       x.dept,
       y.location
  FROM (SELECT p.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM patinet) p
  JOIN pdetails x ON p.pid = x.pid  AND x.isactive = 1
  JOIN (SELECT y.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM plocation y) y
            ON y.idr = p.idr
           AND y.idc = p.idc
           AND y.idopstype in (36, 37)
           AND y.rn = 1
   JOIN (SELECT y.*, RANK() OVER(PARTITION BY ids, idc ORDER BY id) rn FROM plocation_log yt) yt
            ON yt.idr = y.idr
           AND yt.idc= y.idc
           AND yt.idopstype in (36,37)
           AND yt.rn = 1
WHERE
   p.idp IN (10,20,30)
   AND p.idopstype in (36,37)
   AND p.rn = 1
   

---

考虑加入聚合CTE，以计算每个组的

MAX

值一次，而不是为每个外部查询行按行计算

MAX

。此外，请确保使用信息更丰富的表格别名，而不是

a、b、c

或

x、y、z

样式

WITH loc_max AS
  (select ids, idc, max(id) as max_id from plocation group ids, idc)    
 ,   log_max AS    
  (select ids, idc, max(id) as max_id from plocation_log group by ids, idc)
 ,   pat_max AS
  (select ids, idc, max(id) as max_id from patent pr group by ids, idc)

SELECT to_char(pat.pid) AS patentid
       , pat.name
       , det.dept
       , loc.location
  FROM patent pat
  JOIN pdetails det
    ON pat.pid  = det.pid  
    AND det.isactive = 1
  JOIN plocation loc
    ON  loc.idr = pat.idr
    AND loc.idc = pat.idc
    AND loc.idopstype IN (36, 37)
  JOIN loc_max                              -- ADDED CTE JOIN
    ON  loc.id  = loc_max.max_id
    AND loc.ids = loc_max.ids 
    AND loc.idc = loc_max.idc
   
  JOIN plocation_log log
    ON  log.idr = log.idr
    AND log.idc = log.idc
    AND log.idopstype in (36,37)
  JOIN log_max                              -- ADDED CTE JOIN
    ON  log.id  = log_max.max_id
    AND log.ids = log_max.ids
    AND log.idc = log_max.idc

  JOIN pat_max                              -- ADDED CTE JOIN
    ON  pat.id  = pat_max.max_id
    AND pat.ids = pat_max.ids 
    AND pat.idc = pat_max.idc

WHERE pat.idp IN (10, 20, 30)
  AND pat.idopstype IN (36, 37)

---

考虑加入聚合CTE，以计算每个组的

MAX

值一次，而不是为每个外部查询行按行计算

MAX

。此外，请确保使用信息更丰富的表格别名，而不是

a、b、c

或

x、y、z

样式

WITH loc_max AS
  (select ids, idc, max(id) as max_id from plocation group ids, idc)    
 ,   log_max AS    
  (select ids, idc, max(id) as max_id from plocation_log group by ids, idc)
 ,   pat_max AS
  (select ids, idc, max(id) as max_id from patent pr group by ids, idc)

SELECT to_char(pat.pid) AS patentid
       , pat.name
       , det.dept
       , loc.location
  FROM patent pat
  JOIN pdetails det
    ON pat.pid  = det.pid  
    AND det.isactive = 1
  JOIN plocation loc
    ON  loc.idr = pat.idr
    AND loc.idc = pat.idc
    AND loc.idopstype IN (36, 37)
  JOIN loc_max                              -- ADDED CTE JOIN
    ON  loc.id  = loc_max.max_id
    AND loc.ids = loc_max.ids 
    AND loc.idc = loc_max.idc
   
  JOIN plocation_log log
    ON  log.idr = log.idr
    AND log.idc = log.idc
    AND log.idopstype in (36,37)
  JOIN log_max                              -- ADDED CTE JOIN
    ON  log.id  = log_max.max_id
    AND log.ids = log_max.ids
    AND log.idc = log_max.idc

  JOIN pat_max                              -- ADDED CTE JOIN
    ON  pat.id  = pat_max.max_id
    AND pat.ids = pat_max.ids 
    AND pat.idc = pat_max.idc

WHERE pat.idp IN (10, 20, 30)
  AND pat.idopstype IN (36, 37)

---

您能提供关于表定义的详细信息吗？如果您使用窗口函数而不是相关子查询来重新表述查询，它将运行得更快。您的Oracle版本是否支持windows函数（

OVER

子句）？Oracle从8i:）开始支持窗口分析函数。我认为没有人使用旧版本。请向我们展示表上的索引。@谢谢。我喜欢这个建议，对于我的实例，您是否碰巧有一个带有窗口函数而不是相关子查询的示例来获取唯一Id？您能否提供有关表定义的详细信息？如果您使用窗口函数而不是相关子查询来重新表述查询，它将运行得更快。您的Oracle版本是否支持windows函数（

OVER

子句）？Oracle从8i:）开始支持窗口分析函数。我认为没有人使用旧版本。请向我们展示表上的索引。@谢谢。我喜欢这个建议，你是否碰巧有一个窗口函数的例子，而不是我的实例的相关子查询，以获得唯一的Id请？我喜欢这种方法。显然，解释计划显示的成本比我之前的查询要高一些。不知道为什么，但实际上你的方法是有意义的。考虑索引<代码>连接< /代码>列。无论解释计划由于CTE和new

JOIN

s而显示更多步骤，查询整体运行是否较慢？是。这确实很慢。我已经结束了以另一种方式重写查询的过程，并且看起来很有效。谢谢你的帮助。我喜欢这种方法。显然，解释计划显示的成本比我之前的查询要高一些。不知道为什么，但实际上你的方法是有意义的。考虑索引<代码>连接< /代码>列。无论解释计划由于CTE和new

JOIN

s而显示更多步骤，查询整体运行是否较慢？是。这确实很慢。我已经结束了以另一种方式重写查询的过程，并且看起来很有效。谢谢你的帮助。