Db2 query too fast!!

Posted on 2003-03-09
Medium Priority
Last Modified: 2008-02-26
I need a db2 select query that takes a lot of time to execute. Any ideas on bad practices in db2 that will cause the database to really kill itself (in the order of minutes). I have a million records in 1 table which is refrenced in 3 different tables.

I know like's take time. Also not's. What about group by's and sort's etc etc etc.

Help!! Anything you did to speed up your db2 select query tell me so I can do the opposite.
Question by:John_Doe3rd
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Expert Comment

ID: 8099701
can you put your SQL here?

Author Comment

ID: 8099736
I have no idea what SQL to write. I will create my sql query once I know what is really takes time to execute. Right now im quite open to writing any sql which takes a lot of time. I know this isn't exactly a really precise question, but im just looking for in general stuff that will slow down a query to a point where it will take minutes on a query.

This is db2 running on a 1GHz with 1GB RAM. Just imagine how absurd a question this is.

Accepted Solution

ornicar earned 300 total points
ID: 8099776
What about:

select * from MyTable A, MyTable B
where A.Column1 like concat("*",B.Column1)

Maybe not dirty enough but it is a starting point.
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Expert Comment

ID: 8100669
LOL ornicar i love it.

To be even worse, add a few more *'s to the select list ("select *,*,*,* from..."). He he.


Expert Comment

ID: 8101737
Good idea!

I thought about adding some weird order by:

select *,*,*,*,* from MyTable A, MyTable B
where A.Column1 like concat("*",B.Column1)
order by right(A.Column1,length(A.Column1) - 1)

Should keep the computer busy for a while.

Author Comment

ID: 8137186


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