On Thu, Feb 16, 2023 at 10:03 AM David Rowley <dgrowle...@gmail.com> wrote:
> I suspect it's slower because the final sort must sort the entire > array still without knowledge that portions of it are pre-sorted. It > would be very interesting to improve this and do some additional work > and keep track of the "memtupsortedto" index by pushing them onto a > List each time we cross the availMem boundary, then do then qsort just > the final portion of the array in tuplesort_performsort() before doing > a k-way merge on each segment rather than qsorting the entire thing > again. I suspect this would be faster when work_mem exceeds L3 by some > large amount. Sounds like a reasonable thing to try. It seems like in-memory merge could still use abbreviation, unlike external merge. -- John Naylor EDB: http://www.enterprisedb.com
