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Rewrite the SQL using With Clause (Subquery factoring)

Posted on 2009-05-18
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Last Modified: 2013-12-19
Experts -

Please help me to rewrite this query using oracle With Clause.

Thanks.
SELECT col1

FROM table1 i

WHERE i.i_id IN

  (SELECT im.i_id

  FROM table2 im

  WHERE im.index_code = 'XXX'

  AND im.start_date  <= DATE '2007-03-01'

  AND (im.end_date   IS NULL

  OR im.end_date     >= DATE '2007-03-02')

  )

AND i.start_date <= DATE '2007-03-01'

AND (i.end_date  IS NULL

OR i.end_date    >= DATE '2007-03-02')

AND NOT EXISTS

  (SELECT t1.i_id

  FROM table3 t1

  WHERE t1.i_id = i.i_id

  AND (t1.timeseries_date + t1.timeseries_time) BETWEEN TIMESTAMP '2007-03-01 10:00:00' AND TIMESTAMP '2007-03-02 10:00:00'

  AND t1.avg_pcol1e = 0.00

  )

AND EXISTS

  (SELECT t2.i_id

  FROM table3 t2

  WHERE t2.i_id = i.i_id

  AND (t2.timeseries_date + t2.timeseries_time) BETWEEN TIMESTAMP '2007-03-01 10:00:00' AND TIMESTAMP '2007-03-02 10:00:00'

  )

AND i.col1 NOT IN ('AAA', 'BBB')

ORDER BY col1

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Question by:sventhan
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24417165
can you explain the WHY you want to do that?
0
 
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Author Comment

by:sventhan
ID: 24417244
Trying to fix some performance issue.
Try to eliminate the SubQuries.
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Author Comment

by:sventhan
ID: 24417433
Please delete the question. I found a solution.
0
 
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Expert Comment

by:sdstuber
ID: 24418054
I hope what you found is that WITH won't help you here.
And that your query needs fixed logically before fixed performance wise.


The  query "as is" looks for i_id  from table1  that both DOES and DOES NOT exist in the same time range of table3.

Obviously, nothing satisfies that so there must be a logic problem
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Author Comment

by:sventhan
ID: 24418097
thanks SD for your reply.
I've attached the real query and still do you think there is a logic issue.
I'm looking for a way to rewrite the query.
 

pt-sqls.txt
0
 
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Expert Comment

by:sdstuber
ID: 24418109
oops, I didn't notice the avgerage price clause in the original.   so your exists and your not exists are in fact different.
my mistake.  sorry.

you can still delete the question, but if you found an interesting solution, please post it and then accept your own answer to close the question for a PAQ
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Author Comment

by:sventhan
ID: 24418110
the difference between exists and not exists is this row
"  AND t1.avg_price = 0.00"
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Author Comment

by:sventhan
ID: 24418117
Still I'm stuggling with my version of code.
Can you give me your own version/advice if you have time?
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Author Comment

by:sventhan
ID: 24418153
here is my version of code...
 

pt-sql-myver.txt
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Accepted Solution

by:
sdstuber earned 500 total points
ID: 24418198
I wouldn't bother using WITH as a performance tool since your factored-query must be correlated to the instruments table and you have two different conditions to apply to that correlation.
It's not really going to do anything for you.

In fact, if you do an explain plan you should be able to see your refactoring show up as view steps in your plan.

Please post your plan for your original and your modified versions
along with the ddl for the tables and the indexes.
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Author Comment

by:sventhan
ID: 24418228
Sure SD.
I'll do that as soon as I've access to the system at work.
another question, where can I find your presentation for collaborate 09? You did not post the link at your memeber profile.
Thanks so much for the help.
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Expert Comment

by:sdstuber
ID: 24418321
you already figured it out.  :)  just email me if you'd like a copy.
0
 
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Author Comment

by:sventhan
ID: 24418385
Thanks SD.
This the final version of my code.
I'll post the explain plan details later.
 

pt-sql-myver.txt
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Author Closing Comment

by:sventhan
ID: 31582807
Thanks for the suggestions. I do not see any big performance improvements as you stated. I liked your powerpoint presentation that was super. What I was asking is your URL (blog) or something where you keep all your oracle articles on web. It would be really useful to lots of people.
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Expert Comment

by:sdstuber
ID: 24432923
glad I could help, and glad you enjoyed the article and ppt.  Thanks!

I don't currently maintain a blog.  Since I started on EE, I average 15-20 posts per day, so that's all the blogging I can handle.  :)  I am ramping down signficantly on EE though.  So I will be getting more time for other projects.

I have been asked many times to start a blog and when I do, I'll update my EE profile to point to it.
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