Re: Randomisation for ensuring nlogn complexity in quicksort

From: Atri Sharma <atri(dot)jiit(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: PgHacker <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Randomisation for ensuring nlogn complexity in quicksort
Date: 2013-07-02 12:04:37
Message-ID: CAOeZVidTsYUL57Mjp0iPaXZ=5OOoeGfr4Sx_pAk805yixz+TjQ@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Tue, Jul 2, 2013 at 5:20 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Jul 2, 2013 at 12:33 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> wrote:
>>> If you want to get a useful response to your emails, consider
>>> including a statement of what you think the problem is and why you
>>> think your proposed changes will help. Consider offering a test case
>>> that performs badly and an analysis of the reason why.
>>
>> Right, thanks for that. I will keep that in mind.
>>
>> I was thinking about *mostly sorted* datasets, consider the following:
>>
>> 10 11 12 4 5 6 1 2
>
> I think if you'll try it you'll find that we perform quite well on
> data sets of this kind - and if you read the code you'll see why.

Right, let me read the code again from that viewpoint.

Thanks a ton for your help!

Regards,

Atri

--
Regards,

Atri
l'apprenant

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Peter Eisentraut 2013-07-02 12:36:59 Re: Review: query result history in psql
Previous Message Andres Freund 2013-07-02 12:03:46 Re: Eliminating PD_ALL_VISIBLE, take 2