Re: Experience in bitmap index in Oracle 7.3

More experience:

MS Access apparently cannot link to files with BMI's defined. Link first, then add indexes, seems to work. TAR submitted.

BMI processing is still not very smart, apparently. I did a count on a 1,000,000 row table for a value of a col. that was bit-mapped indexed that didn't exist. Took 20 secs to figure out "no rows returned", same as when the value did exist.

Also, when this table was linked to a lookup table (Country name linked via country code in the main table) and the WHERE was on country name, query time went from :20 to 2:40. Again, all cols bitmapped--seems like it would be possible to do this with zero added time using the BMI's.

Has anyone seen any docco regarding when and how the query optimizer ACTUALLY uses BMI's?

Brad W. Skiles wrote:
>
> We've begun implementing bitmaps on our 7.3.2.3 HP-UX system. The
> experience has been good and bad.
>
> Good
> --------
> Storage improvements have been dramatic. An index on a fiscal_year

Yes--I second that observation. Received on Fri Feb 07 1997 - 00:00:00 CST