2023年9月28日 12:26，David G. Johnston <david.g.johnston@gmail.com> 写道：
On Wednesday, September 27, 2023, jacktby jacktby <jacktby@gmail.com> wrote:
postgres=# SET enable_seqscan = off; SET postgres=# explain select * from t; QUERY PLAN ------------------------------------------------------------------------- Seq Scan on t (cost=10000000000.00..10000000023.60 rows=1360 width=32)
It wouldn’t cost 10billion to return the first tuple if that setting wasn’t working.
That is the “discouragement” the documentation is referring to.
I do agree the wording in the docs could be improved since it is a bit self-contradictory and unspecific, but it is explicitly clear a plan with sequential scan can still be chosen even with this set to off.