[Bizgres-general] A bitmap index access method is available in bizgres CVS tip

[Sam Vilain]

On Tue, 2005-12-13 at 02:25 -0500, Jie Zhang wrote:
> A bitmap index access method is now available in bizgres CVS tip. The
> bitmap index is a highly efficient structure to index high dimensional
> data, especially when the attributes to be indexed have very low
> cardinalities.

Apparently on Oracle, the value of "low" here is something like 2^20.
Apparently this is because as the cardinality increases, the
compressibility (presumably RLE) of the indexes increases drastically.

Has any work been done to quantify what "low" is ?

Sam.