| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Neil Conway <neilc(at)samurai(dot)com> |
| Cc: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Which qsort is used |
| Date: | 2005-12-12 22:47:37 |
| Message-ID: | 2373.1134427657@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Neil Conway <neilc(at)samurai(dot)com> writes:
> BTW, Luke Lonergan recently posted some performance results for a fairly
> efficient public domain implementation of qsort to the bizgres list:
> http://lists.pgfoundry.org/pipermail/bizgres-general/2005-December/000294.html
As those results suggest, there can be huge differences in sort
performance depending on whether the input is random, nearly sorted,
nearly reverse sorted, possesses many equal keys, etc. It would be very
dangerous to say "implementation A is better than implementation B"
without having tested all those scenarios. IIRC, the reason we reject
Solaris' qsort is not that it is so bad in the typical case, but that it
has some horrible corner-case behaviors.
regards, tom lane
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