Tuning a Self-Join sql query

[slimdave]

Here's a couple of alternatives that might be worth trying. No promises, mind. The second one would benefit from a composite (col1,col2) index, I would think

Select Distinct
   a.col1,
   a.col2
From
   table1 a,
   table1 b,
Where
   a.col1 = b.col1 And
   a.col2!= b.col2
/

Select
   col1,
   col2
From
   (
   Select
      col1,
      col2,
      Count(Distinct col1) Over
         (Partition By col1) cd_col2
   From
      table1
   Where
      col1 is not null
   )
Where cd_col2 > 1