This is not correct. An index can accelerate, for instance, max(). Here is also not WHERE or ORDER BY, but index is useful: select max(created_at) from delivery;
> 23 окт. 2023 г., в 18:23, Toomas <toomas.kris...@gmail.com> написал(а): > > > There is no reason to use index. The query has neither WHERE nor ORDER BY > clause. > > Toomas > >> On 23. Oct 2023, at 18:13, Олег Самойлов <spl...@ya.ru> wrote: >> >> Back pardon, but I have a very newbie question. I have a partitioned table, >> partitioned by primary bigint key, size of partition 10000000. I need to get >> the number of partition which need to archive, which has all rows are olden >> then 3 month. Here is query: >> >> SELECT id/10000000 as partition >> FROM delivery >> GROUP BY partition >> HAVING max(created_at) < CURRENT_DATE - '3 month'::interval; >> >> The 'id/10000000 as partition' is a number of the partition, it later will >> be used inside the partition name. >> The query runs long by sequence scan. Has anyone any ideas how to rewrite >> query so it will use any index? >> >
