[英]Oracle query optimization recommendation
下面的查询只需要很长时间,下面的谓词仅用于获取唯一记录,因此想知道是否有不同的方法来重写相同的查询,而无需多次调用下面的谓词来获取唯一 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 The Impaler 所评论的,一种选择是使用分析函数而不是相关子查询。 这个想法是使用RANK()
查询中的记录进行排名,然后在外部查询(连接条件或WHERE
子句)中进行过滤。
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进行行MAX
计算。 此外,请务必使用信息量更大的表别名,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)
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