David G. Johnston <david.g.johns...@gmail.com> 于2025年8月4日周一 12:33写道：
> On Sun, Jul 27, 2025 at 12:53 AM Tender Wang <tndrw...@gmail.com> wrote: > >> >> We can merge the two scans into one. This can reduce the time complexity >> from 2O(n) to O(n). >> > > This seems like an unusual usage of big-O notation. Always saw the > meaningful pieces inside the O, and in general I thought O(n) =~ O(xn) for > all x, but especially if x is small. > > The point made by Chao Li, that by using a loop guard we avoid performing > expression evaluation, seems like a reasonable and sufficient non-data > supported reason for having the code structured this way. I'd at least > want a more data-driven reason to try and change it in such a simple way > against the read/write boundary that presently exists. > Agree, I will withdraw the patch. > > I was pondering whether contain_volatile_functions could/should be taught > to also detect whether every expression it sees resolves to a constant... > contain_volatile_functions((Node *) rte->values_lists, &has_non_constants) > > But got a little ways down the call stack and hit the "walker" macro and > decided to stop... > > >> Also, add a brace for better/more consistent style in the attached patch. >> > > Should try and avoid oh-by-the-way fixes like this in behavior patches. > > This specific one also doesn't seem warranted. Or, at least, the original > style is indeed de facto acceptable; if-blocks containing a single > executing statement do not get braces but rely on indentation alone. I > don't think that every other if-block in the region being multi-statement > supports an exception. > About this, you can check this commit https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=aadf7db66ef5a8a723eb3362e2c8b460738f1107 . Add brace for better/more consistent style. -- Thanks, Tender Wang
