Did you do an explain? I'd guess the index isn't being used because of
skewed statistics.
> i have a btree index on col1 in table1. The column has either values
> 1,2,3, or 4. 4 does not appear that much in the table (only 5 times).
> there are about 20 million rows in the table. when i do a "select *
> from table1 where col1=4" it takes very long time to get back to me
> (around 4 minutes). why is it taking so long if i have an index on
> it? I also tried this with a hash index and it was still slow.
