Solved

Rewrite the SQL using With Clause (Subquery factoring)

Posted on 2009-05-18
15
673 Views
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

Open in new window

0
Comment
Question by:sventhan
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 9
  • 5
15 Comments
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24417165
can you explain the WHY you want to do that?
0
 
LVL 18

Author Comment

by:sventhan
ID: 24417244
Trying to fix some performance issue.
Try to eliminate the SubQuries.
0
 
LVL 18

Author Comment

by:sventhan
ID: 24417433
Please delete the question. I found a solution.
0
Creating Instructional Tutorials  

For Any Use & On Any Platform

Contextual Guidance at the moment of need helps your employees/users adopt software o& achieve even the most complex tasks instantly. Boost knowledge retention, software adoption & employee engagement with easy solution.

 
LVL 74

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
0
 
LVL 18

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
 
LVL 74

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
0
 
LVL 18

Author Comment

by:sventhan
ID: 24418110
the difference between exists and not exists is this row
"  AND t1.avg_price = 0.00"
0
 
LVL 18

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?
0
 
LVL 18

Author Comment

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

pt-sql-myver.txt
0
 
LVL 74

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.
0
 
LVL 18

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.
0
 
LVL 74

Expert Comment

by:sdstuber
ID: 24418321
you already figured it out.  :)  just email me if you'd like a copy.
0
 
LVL 18

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
0
 
LVL 18

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.
0
 
LVL 74

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.
0

Featured Post

Salesforce Has Never Been Easier

Improve and reinforce salesforce training & adoption using WalkMe's digital adoption platform. Start saving on costly employee training by creating fast intuitive Walk-Thrus for Salesforce. Claim your Free Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Cursors in Oracle: A cursor is used to process individual rows returned by database system for a query. In oracle every SQL statement executed by the oracle server has a private area. This area contains information about the SQL statement and theā€¦
From implementing a password expiration date, to datatype conversions and file export options, these are some useful settings I've found in Jasper Server.
This video explains at a high level with the mandatory Oracle Memory processes are as well as touching on some of the more common optional ones.
This video shows how to Export data from an Oracle database using the Original Export Utility.  The corresponding Import utility, which works the same way is referenced, but not demonstrated.
Suggested Courses

623 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question