Usually Adhoc reporting is allowed against a Data Warehouse not against an OLTP system - is this an OLTP system, init?
Allowing adhoc reporting against this structure might cripple the system as a whole.
I would suggest to create a star-schema datamart in a different environment then allow reporting against it.
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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.