我如何看待PostgreSQL约束上的注释?

\dd <constraint_name> 应显示注释,但不按表名筛选。

您可以使用系统目录 pg_constraint 和 pg_description 查询约束的注释。

带有约束注释的示例表:

create table test(
    id int unique,
    str text check(str <> '')
);

comment on constraint test_id_key on test is 'my comment on test_id_key';
comment on constraint test_str_check on test is 'my comment on test_str_check';

选择表约束的所有注释 test 以下内容:

select c.relname, t.conname, d.description
from pg_class c
join pg_constraint t on c.oid = t.conrelid
join pg_description d on t.oid = d.objoid and t.tableoid = d.classoid
where c.relname = 'test'

 relname |    conname     |         description          
---------+----------------+------------------------------
 test    | test_str_check | my comment on test_str_check
 test    | test_id_key    | my comment on test_id_key
(2 rows)