From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Performance of ORDER BY |
Date: | 2006-12-05 18:39:16 |
Message-ID: | 9446.1165343956@sss.pgh.pa.us |
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Lists: | pgsql-performance |
"Steinar H. Gunderson" <sgunderson(at)bigfoot(dot)com> writes:
> By the way, is the new sorting code any better for platforms that already
> have a decent qsort() (like Linux)?
It seemed better to us. Linux' qsort() is really mergesort, which is
better sometimes but often worse --- mergesort tends to have a less
CPU-cache-friendly memory access distribution. Another big problem with
the Linux version is that it pays no attention to sort_mem, but will
enthusiastically allocate lots of additional memory, thereby blowing
whatever cross-backend memory budgeting you might have been doing.
If you care there is quite a lot of discussion in the -hackers and
-performance archives from last spring or so.
regards, tom lane
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