On Tue, Feb 14, 2023 at 5:46 PM David Rowley <[email protected]> wrote: > > I didn't do a detailed review of the sort patch, but I did wonder > about the use of the name "fallback" in the new functions. The > comment in the following snippet from qsort_tuple_unsigned_compare() > makes me think "tiebreak" is a better name.
I agree "tiebreak" is better. > I also wonder if the weirdness I reported in [1] would also disappear > with your patch. There's a patch on that thread that hacks up the > planner to split multi-column sorts into Sort -> Incremental Sort > rather than just a single sort. I tried that test (attached in script form) with and without the tiebreaker patch and got some improvement: HEAD: 4 ^ 8: latency average = 113.976 ms 5 ^ 8: latency average = 783.830 ms 6 ^ 8: latency average = 3990.351 ms 7 ^ 8: latency average = 15793.629 ms Skip rechecking first key: 4 ^ 8: latency average = 107.028 ms 5 ^ 8: latency average = 732.327 ms 6 ^ 8: latency average = 3709.882 ms 7 ^ 8: latency average = 14570.651 ms I gather that planner hack was just a demonstration, so I didn't test it, but if that was a move toward something larger I can run additional tests. The configuration was (same as yesterday, but forgot to mention then) turbo off shared_buffers = '8GB'; work_mem = '4GB'; max_parallel_workers = 0; -- John Naylor EDB: http://www.enterprisedb.com
bench_cartesiansort.sh
Description: application/shellscript
