On Mon, Nov 5, 2012 at 2:09 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>>> In my experience when doing sorts in isolation, having more work_mem
>>> is a bad thing, unless it enables you to remove a layer of
>>> tape-merging. I always blamed it on the L1/L2 etc. levels of caching.
>>
>> Blame it on quicksort, which is quite cache-unfriendly.
>
> The observation applies to heap sort.
Well, heapsort is worse, but quicksort is also quite bad.