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POHow to optimize huge query with repeated subqueries
 

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  1. POHow to optimize huge query with repeated subqueries
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    <p>I have the following huge query that contains repeated subqueries , It looks really inefficient to me. How can i optimize it ?</p> <pre><code>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 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1) AND S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1) AND S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1) AND S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1) AND S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1) AND S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' ) ORDER BY date1,date2,period,market,ticker </code></pre> <p>After @<a href="https://stackoverflow.com/users/99003/bruce-alderson">Bruce</a> 's comment and some logic to reduce a subquery my query now is:</p> <pre><code>(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 &gt;= (@date1 := '2009-09-01') AND S.date2 &lt;= (@date2 := '2010-07-01') AND Q.date = (@qdate := '2010-07-01') AND S.series = (@series := (SELECT S.series FROM scenario S WHERE S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '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 &gt;= @date1 AND S.date2 &lt;= @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 &gt;= @date1 AND S.date2 &lt;= @date2 )) </code></pre> <p>However, If i changed </p> <pre><code> (@series := (SELECT S.series FROM scenario S WHERE S.date1 &gt;= '2009-09-01' AND S.date2 &lt;= '2010-07-01' AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1)) </code></pre> <p>to be</p> <pre><code> (@series := (SELECT S.series FROM scenario S WHERE S.date1 &gt;= @date1 AND S.date2 &lt;= @date2 AND S.period = 'QUARTER' ORDER BY S.date2 LIMIT 1)) </code></pre> <p>It takes too much time to process it (i have executed the query 10 mins ago and still did not get the result) while the query normally returns in 5 seconds.</p> <p>Also when i reset the variables , execute the result is not correct (probably use the variable's value from the previous execution). How can i change that without adding SET statements (I would like it to be a single query)</p>
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