Re: Sort time

Hi,

Stephan Szabo wrote:

> On Sat, 16 Nov 2002, pginfo wrote:
>
> > Hi,
> >
> > Tom Lane wrote:
> >
> > > Josh Berkus <josh(at)agliodbs(dot)com> writes:
> > > > Here's a question: is the total size of the column a good indicator of the
> > > > sort_mem required? Or does the rowsize affect it somehow?
> > >
> > > It will include all the data that's supposed to be output by the sort...
> > > both the key column(s) and the others.
> > >
> >
> > Hmm it is not clear for me.Let we have all data.
> > If I make sort by S.OP ( it is INT) it take < 6 sek for sort.
> > I think we move all this data anly the number of comparation is by INT. I think
> > the number of comparation
> > is ~ n * ln(n).
> > If we sort by S.IDS_xxx we have also n*ln(n) comparations but in
> > varchar(string).
> > I don't think that it can take 50 sek.
> >
> > Is it not so?
>
> Have you tried setting up another database in "C" locale and compared the
> timings there? I'd wonder if maybe there's some extra copying going on
> given the comments in varstr_cmp.

No, I do not have any info about it.I will see if it is possible ( the data are not
so simple).
If it is possible I will make the tests.
Have no one that have 700K row in thow tables?
It is simple to test:
1. Run query that returns ~700K rows from this tables.
2. Make sort.

It is interest only the sort time!

regards,
Ivan.