| From: | pginfo <pginfo(at)t1(dot)unisoftbg(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | josh(at)agliodbs(dot)com, Rod Taylor <rbt(at)rbt(dot)ca>, "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Sort time |
| Date: | 2002-11-16 06:36:52 |
| Message-ID: | 3DD5E784.BA4FF2D7@t1.unisoftbg.com |
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| Lists: | pgsql-performance |
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?
regards,
ivan.
> regards, tom lane
>
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