On 14/11/14 00:46, Simon Riggs wrote:
> Limit (cost=.... rows=20 width=175) (actual time=.... rows=20 loops=1)
> -> Sort (cost=.... rows=568733 width=175) (actual time=....
> rows=20 loops=1)
> Sort Method: top-N heapsort
Going off on a tangent, when I was playing with a merge-sort
implementation I propagated limit information into the sort
node, for a significant win. Eliding the Limit node gave
a further slight win.
I wasn't convinced the use-case was common enough to justify
the replacement of quicksort (despite having consistently
fewer compares, the merge sort was slightly slower. I never
understood why) - but I never asked. Is there any appetite
for supporting alternate sort algorithms?
--
Cheers,
Jeremy