Re: PG qsort vs. Solaris

On Tue, Oct 03, 2006 at 03:44:38PM -0400, Tom Lane wrote:
> select count(*) from
>   (select random()::text from generate_series(1,1000000) order by 1) ss;
> ...
> postgres=# select count(*) from (select random() from generate_series(1,1000000) order by 1) ss;

I'm wondering whether 'order by 1' is representative of a real sort, from
the perspective of benchmarks.

I wonder why 'order by CONSTANT' might not be safe to optimize away as
no sort at all?

For sort functions that incrementally improve the sort order, I would
expect 'order by 1' to be a worst case scenario. Is that the intention?
Or is qsort unaffected by this use?

Cheers,
mark

-- 
mark@mielke.cc / markm@ncf.ca / markm@nortel.com     __________________________
.  .  _  ._  . .   .__    .  . ._. .__ .   . . .__  | Neighbourhood Coder
|\/| |_| |_| |/    |_     |\/|  |  |_  |   |/  |_   | 
|  | | | | \ | \   |__ .  |  | .|. |__ |__ | \ |__  | Ottawa, Ontario, Canada
 One ring to rule them all, one ring to find them, one ring to bring them all                      and in the darkness
bindthem...
 
                          http://mark.mielke.cc/