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If you are thinking in bitmap indexes you are probably thinking in doing star-transformation on a FACT table.
If this is the case it doesn't make any sense to test with a single index; your FACT table would probably have tens of bitmap indexes.
Do yourself a big favor and test on at least a 50 columns table with 30 bitmap indexes; 25 million rows or so. Your simulated ETL process should touch not least than 10% of the rows.
I would suggest not only look at the improvement in performance but also at the size of the bitmap indexes before and after the ETL simulation.
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
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