Re: Bitmap or B-Tree indexes...?

Aftermath Fan wrote:
> Hi,
>
> I have a table with about 120 million rows. I'd like to index two
> columns. Column id1 has about 15,000 distinct values; column id2 has
> about 600,000. Most of the queries are:
>
> select <something> from <table> where id1 = ?
> select <something> from <table> where id2 = ?
> select <something> from <table> where id1 = ? and id2 = ?
>
> I'm thinking for id1, the column with 15,000 values, a bitmap index
> would be appropriate given its low relative cardinality. And for id2
> and (id1,id2) a B-tree index.
>
> Just looking for a sanity check...thanks.

I'm thinking an explain plan created with DBMS_XPLAN would be the first step. Well that and a version number. ;-)

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
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Puget Sound Oracle Users Group
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