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

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