Ruled Bsed optimization in DB2

[bean1234]

Hello Experts,

I have a question regarding the ruled based optimization techniques used in DB2 ,if we have a set of conditions in the where clause, is there anyway we can affect the way those conditions are applied...

Like if we have "where condition1 and condition2" etc and we know that condition 2 will results in filtering out the most number of rows and we want condition2 to be aplied first , does it have to be listed first in the where clause like "where condition2 and condition1"

I know this can be figured out by using the Access Plan , but I am new to DB2 and have never used the DB2 Explain.

 

[fredericofonseca]

Normally predicates that reduce most the records being returned should be placed before the others.

if you have the columns in question "runstated", then they will be used accordingly also to help the plan used.

Regards

Frederico Fonseca
SysSoft Integrated Ltd

http://www.syssoft-int.com

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