Hi Cantika, By going through all the discussions, following are my thoughts to resolve/ reduce the time of processing. 1. Since your matching key is sex ( M, F ,not sure if you've transgender also ) , based on this you can split both your tables into two tables(both case, control). You don't need to create the table physically. Creating view would suffice. 2. The next step is to understand the age. I'm sure you should have an idea of the cardinality of age in case, (age_lo and age_hi) in control. 3. After identifying step 1, 2 you can create equal no of records in each table. For example 65,000 obs into 10 X 6500, 10 x 0.7M records. 4. After doing all this you can do parallel processing. The following sugi paper might help you doing that. http://www2.sas.com/proceedings/sugi29/124-29.pdf I don't think there is a bitmap index in sas like in oracle to help low cardinality key performance. Hope this helps.
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