Holger Baer wrote:
> Kirtan Acharya wrote:
> > Hi,
> > I'd like to add that this query will retrieve numbers only till the
9th
> > power of 2 i.e. 512. So if u need higher numbers, keep on adding
digits
> > to the end of the list
> > group by cube(1,2,3,4,5,6,7,8,9,10,11,12....)
> >
> > hope this helps,
> > kirtan
> >
>
> This is true, but performance is rapidly declining. For larger
numbers,
> you're better off by creating cartesian products from two or more
cubes.
>
> At least for my test machine:
>
> 1 select count(*) from (select 1 from dual group by
cube(1,2,3,4,5,6,7,8,9,10
>
> ))
> 2* , (select 1 from dual group by cube (1,2,3,4,5,6,7,8,9,10))
> baer_at_DEMO10G>/
>
> COUNT(*)
> ----------
> 1048576
>
> Elapsed: 00:00:00.21
>
> baer_at_DEMO10G>select count(*) from (select 1 from dual group by
cube(1,2,3,4,5,6,
>
> 7,8,9,10,11,12,13,14,15));
>
> COUNT(*)
> ----------
> 32768
>
> Elapsed: 00:01:05.23
> baer_at_DEMO10G>/
>
> COUNT(*)
> ----------
> 32768
>
> Elapsed: 00:00:00.22
> baer_at_DEMO10G>select count(*) from (select 1 from dual group by
cube(1,2,3,4,5,6,7,8,9,10,11,12,13,14));
>
> COUNT(*)
> ----------
> 16384
>
> Elapsed: 00:00:00.09
> baer_at_DEMO10G>
>
> So subsequent calls of the larger cube are fast, but the initial call
can be
> really slow. Your treshold might be different from mine, but I'd be
very cautios
> to go beyond 10 before using the cartesian product.
>
> Cheers,
>
> Holger
Received on Thu Jan 20 2005 - 15:12:47 CST
