Hi, Andrei! On Fri, Jul 12, 2024 at 6:05 AM Andrei Lepikhov <lepi...@gmail.com> wrote: > > On 7/11/24 14:43, jian he wrote: > > On Tue, Jul 9, 2024 at 2:06 PM Andrei Lepikhov <lepi...@gmail.com> wrote: > >> > >> On 7/2/24 07:25, jian he wrote: > >>> to make sure it's correct, I have added a lot of tests, > >>> Some of this may be contrived, maybe some of the tests are redundant. > >> Thanks for your job! > >> I passed through the patches and have some notes: > >> 1. Patch 0001 has not been applied anymore since the previous week's > >> changes in the core. Also, there is one place with trailing whitespace. > > > > thanks. > > because the previous thread mentioned the EPQ problem. > > in remove_useless_self_joins, i make it can only process CMD_SELECT query. > I would like to oppose here: IMO, it is just a mishap which we made > because of a long history of patch transformations. There we lost the > case where RowMark exists for only one of candidate relations. > Also, after review I think we don't need so many new tests. Specifically > for DML we already have one: > > EXPLAIN (COSTS OFF) > UPDATE sj sq SET b = 1 FROM sj as sz WHERE sq.a = sz.a; > > And we should just add something to elaborate it a bit. > See the patch in attachment containing my proposal to improve v4-0001 > main SJE patch. I think it resolved the issue with EPQ assertion as well > as problems with returning value.
I tried this. I applied 0001 from [1] and 0002 from [2]. Then I tried the concurrent test case [3]. It still fails with assert for me. But assert and related stuff is the least problem. The big problem, as described in [3], is semantical change in query. When EPQ is applied, we fetch the latest tuple of the target relation regardless snapshot. But for the self-joined relation we should still use the snapshot-satisfying tuple. I don't see even attempt to address this in your patch. And as I pointed before, this appears quite complex. Links. 1. https://www.postgresql.org/message-id/96250a42-20e3-40f0-9d45-f53ae852f8ed%40gmail.com 2. https://www.postgresql.org/message-id/5b49501c-9cb3-4c5d-9d56-49704ff08143%40gmail.com 3. https://www.postgresql.org/message-id/CAPpHfduM6X82ExT0r9UzFLJ12wOYPvRw5vT2Htq0gAPBgHhKeQ%40mail.gmail.com ------ Regards, Alexander Korotkov Supabase
