index on null

We have a table with data distribution like this:

            COUNT(*) BUSINESS_UNIT
-------------------- -----

                 539 AB340
             242,808 XY410
                  81 AB941
          11,890,271
              81,494 XY411
              71,532 TY810

Give that majority of the values are null for the Business_unit column, would it make a difference adding an index on the column. Assume the query accesses the table using business_unit column only. So far I am trying to tune the query that supplies values for the bus_unit column. the query is a multi table join; trying to make this specific table driving table.

CP.

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http://www.freelists.org/webpage/oracle-l Received on Fri Aug 28 2015 - 22:15:58 CEST