Em qua., 15 de set. de 2021 às 16:16, Ranier Vilela <ranier...@gmail.com> escreveu:
> Em qua., 15 de set. de 2021 às 15:35, Tom Lane <t...@sss.pgh.pa.us> > escreveu: > >> Ranier Vilela <ranier...@gmail.com> writes: >> > Em qua., 15 de set. de 2021 às 12:00, Tom Lane <t...@sss.pgh.pa.us> >> escreveu: >> >> We could, in fact, not bother with removing the no-longer-referenced >> >> subplans, and it probably wouldn't be all that awful. But the intent >> >> of the original patch was to save the executor startup time for such >> >> subplans, so I wanted to preserve that goal if I could. >> >> > I'm sorry if I'm being persistent with this issue, but I'd like to give >> it >> > one last try before I let it go >> > I modified the way the subplane deletion is done and it seems to me that >> > this really happens. >> >> It looks like what this fragment is doing is clobbering the List >> substructure of the AlternativeSubPlan node itself. That's not >> going to make any difference, since the whole point of the exercise >> is that the AlternativeSubPlan gets cut out of the finished tree. >> But the list that we want to modify, in order to save the >> executor time, is the root->glob->subplans list (which ends >> up being PlannedStmt.subplans). And that's global to the >> query, so we can't fix it correctly on the basis of a single >> AlternativeSubPlan. >> > Ok, I can see now. > But this leads me to the conclusion that AlternativeSubPlan *asplan > does not seem to me to be a good approach for this function, better to > deal with it directly: > "root->glob->subplans" which, it seems, works too. > Hmm, too fast and wrong, do not work. postgres=# explain (costs off) postgres-# select * from exists_tbl t1 postgres-# where (exists(select 1 from exists_tbl t2 where t1.c1 = t2.c2) or c3 < 0); ERROR: unrecognized node type: 13 postgres=# select * from exists_tbl t1 postgres-# where (exists(select 1 from exists_tbl t2 where t1.c1 = t2.c2) or c3 < 0); ERROR: unrecognized node type: 13 regards, Ranier Vilela
