| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | Kefan Yang <starordust(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Fwd: GSOC 2018 Project - A New Sorting Routine |
| Date: | 2018-07-14 01:24:36 |
| Message-ID: | CAH2-Wz=UG59y7aCpmskGfNadjNs5ku6e2_gVWcPk4si9r9whfw@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Fri, Jul 13, 2018 at 6:03 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> Unlikely. The pivot randomization is merely a way to defeat an adversary
> attempting to perform DoS by triggering sorts on a killer sequence.
> Randomization makes it much harder/impossible, because the killer
> sequence changes over time. It's not a regular performance optimization.
+1. The importance of the quadratic worst case for an industrial
strength quicksort seems to often be overstated.
Robert Sedgewick's Algorithms book has *excellent* analysis of
quicksort's worst case, which might be worth a read.
--
Peter Geoghegan
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Justin T Pryzby | 2018-07-14 03:15:34 | Re: Finding database for pg_upgrade missing library |
| Previous Message | Tomas Vondra | 2018-07-14 01:03:21 | Re: Fwd: GSOC 2018 Project - A New Sorting Routine |