Hello, I am Jinho Jung, Phd Student from GeorgiaTech, and try to find any SQL 
queries that cause performance regression. While conducting evaluation, I found 
an interesting query which makes x80 times slower execution in version 10.5 
than version 9.4. Please see the attached files, if you are interested.

To analyze the root cause of problem, I had to find minimal query that contains 
same problem. (i.e., same regression issue) The initial query was about 14K and 
I should manually remove part of query. (it took about 30 minutes to get 500 
bytes query) So I am wondering if there are tools to automatically simplify 
statements to analyze the performance issue.

Thanks,
Jinho Jung

Attachment: query6_manually_minimize
Description: query6_manually_minimize

Attachment: query6_original
Description: query6_original

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