On Thu, Nov 7, 2024 at 7:38 PM Andy Fan <zhihuifan1...@163.com> wrote: > If the delete goes with Index Scan of t_b_idx, we still have the chances > to mark hints on t_b_idx, so that it can be useful during index split?
See for yourself, by using pageinspect. The bt_page_items function returns a "dead" column, which will be true for index tuples that already have their LP_DEAD bit set. The exact rules for when LP_DEAD bits are set are a bit complicated, and are hard to describe precisely. I don't think that your DELETE statement will set any LP_DEAD bits, because the tuples won't be dead until some time after the xact for the DELETE statement actually commits -- it'd have to be some later SELECT statement that runs after the DELETE commits (could be a DELETE statement instead of a SELECT statement but SELECT is more typical). This also has to happen during an index scan or an index-only scan -- bitmap scans don't do it. Plus there are some other obscure rules. -- Peter Geoghegan
