How to properly index multiple fields for faster results
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I have an index that contains ConChainNum, Control, and TransDate, and I just rebuilt the indexes.  The table I'm working with has over 100 million records and the following query returns no results:

    select  * from sbt_pos_sales 
    where   conchainnum = 810 and 
            control = 852013688 and 
            transdate = 20120712

Given that I have an index made specifically with the three fields in the where clause, I really expected an almost immediate result, but it took about half a minute to tell me there where no results.

Can someone explain to me why this index doesn't make it any faster than that, and if I can somehow do it differently to make it faster?