Re: multi-column btree index for real values

On Thu, Oct 03, 2002 at 02:00:30PM -0400, Martin D. Weinberg wrote:
> Folks,
>
> Can someone quickly describe how the btree is implemented for multiple
> columns?  In particular, under what (if any) circumstances is there an
> advantage if the index is over floating point values?

AFAIK, multi-column btrees and simply handled by building a btree of the
first column. Each leaf contains a reference to another btree for the second
column, etc...

btrees are useful for < and > comparisons, meaning that queries saying WHERE
x BETWEEN 1.0 and 1.5 can use the index.
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> There are 10 kinds of people in the world, those that can do binary
> arithmetic and those that can't.