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我有以下包含重复子查询的巨大查询,它对我来说看起来效率很低。我如何优化它?如何使用重复子查询优化庞大查询
SELECT T2.date1, T2.date2, T2.period, T1.market, T1.ticker, 0 AS scenario
FROM
(SELECT DISTINCT
Q.market AS market,
Q.ticker AS ticker
FROM portfolio.scenario S RIGHT JOIN portfolio.quote Q
ON S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
Q.market = S.market AND
Q.ticker = S.ticker
WHERE Q.date = '2010-07-01' AND
S.date1 IS NULL) AS T1
JOIN
(SELECT DISTINCT S.date1, S.date2, S.period
FROM scenario S
WHERE S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01') AS T2
UNION
SELECT S.date1 AS date1,
S.date2 AS date2,
S.period AS period,
Q.market AS market,
Q.ticker AS ticker,
Q.close * EXP(S.ratio) AS scenario
FROM portfolio.scenario S , portfolio.quote Q
WHERE S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
Q.date = '2010-07-01' AND
Q.market = S.market AND
Q.ticker = S.ticker
UNION
SELECT T2.date1, T2.date2, T2.period, T1.market, T1.ticker, 0 AS scenario
FROM
(SELECT DISTINCT
Q.market AS market,
Q.ticker AS ticker
FROM portfolio.scenario S , portfolio.quote Q
WHERE Q.date = '2010-07-01' AND
Q.market = S.market AND
Q.ticker = S.ticker AND
S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01') AS T1
JOIN
(SELECT DISTINCT S.date1, S.date2, S.period
FROM scenario S
WHERE S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01') AS T2
WHERE (T2.date1, T2.date2, T2.period, T1.market, T1.ticker)
NOT IN (SELECT S.date1 AS date1,
S.date2 AS date2,
S.period AS period,
Q.market AS market,
Q.ticker AS ticker
FROM portfolio.scenario S , portfolio.quote Q
WHERE Q.date = '2010-07-01' AND
Q.market = S.market AND
Q.ticker = S.ticker AND
S.series = (SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1) AND
S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01')
ORDER BY
date1,date2,period,market,ticker
@Bruce的评论和一些逻辑,现在减少一个子查询我的查询之后是:
(SELECT S.date1,
S.date2,
S.period,
Q.market,
Q.ticker,
Q.close * EXP(S.ratio) AS scenario
FROM portfolio.scenario S , portfolio.quote Q
WHERE
S.date1 >= (@date1 := '2009-09-01') AND
S.date2 <= (@date2 := '2010-07-01') AND
Q.date = (@qdate := '2010-07-01') AND
S.series =
(@series :=
(SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1)) AND
Q.market = S.market AND
Q.ticker = S.ticker)
UNION
(SELECT T2.date1, T2.date2, T2.period, T1.market, T1.ticker, 0 AS scenario
FROM
(SELECT Q.market, Q.ticker
FROM quote Q
WHERE Q.date = @qdate) AS T1
JOIN
(SELECT DISTINCT S.date1, S.date2, S.period
FROM scenario S
WHERE S.series = @series AND
S.date1 >= @date1 AND
S.date2 <= @date2) AS T2
WHERE (T2.date1, T2.date2, T2.period, T1.market, T1.ticker)
NOT IN
(SELECT S.date1,
S.date2,
S.period,
Q.market,
Q.ticker
FROM portfolio.scenario S , portfolio.quote Q
WHERE Q.date = @qdate AND
Q.market = S.market AND
Q.ticker = S.ticker AND
S.series = @series AND
S.date1 >= @date1 AND
S.date2 <= @date2))
但是,如果我改变
(@series :=
(SELECT S.series
FROM scenario S
WHERE S.date1 >= '2009-09-01' AND
S.date2 <= '2010-07-01' AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1))
是
(@series :=
(SELECT S.series
FROM scenario S
WHERE S.date1 >= @date1 AND
S.date2 <= @date2 AND
S.period = 'QUARTER'
ORDER BY S.date2
LIMIT 1))
需要t处理它很多时间(我已经执行了查询10分钟前,仍然没有得到结果),而查询通常在5秒内返回。
另外,当我重置变量,执行结果不正确(可能使用前一次执行的变量值)。我怎样才能改变这种不添加SET语句(我想这是一个单一的查询)
谢谢你的好建议,但在我的查询中使用@z:=(SELECT * FROM SubTable WHERE x = @x)这样的行大大增加了获取结果集的时间。我已经重新编辑了这个问题,以包含基于您的评论和一些逻辑的新查询以减少子查询 – 3ashmawy 2010-11-19 22:22:39
这些节省来自在许多列中使用该变量(我的示例没有显示,所以我更新了它) 。我最近将这个应用到了一段总结性的SQL,否则它会为多列重复窗口平均计算(子选择+分组函数)。 – 2010-11-19 22:44:30
Thanx兄弟的反馈,是的,我用@series变量的概念。我想你的例子@z:=(SELECT * FROM SubTable WHERE x = @x),SubTable只有一列,因为@z将无法保存来自多列的值。 – 3ashmawy 2010-11-19 23:18:06