<51183341@xxxxxx> writes: > create table t1 (f1 text not null); > create table t2 (f2 text); > create view v as (select t1.f1, t2.f2 from t1, t2); > Given v, How can a find out the t1.f1 has a not null constraint. I assume what you actually mean is you want to know whether the view v will always produce a non-null in that column. That's not that easy. It is true in the above example, but consider for instance create view v as select t1.f1, t2.f2 from t2 left join t1 on ... With the outer join, that view column could produce nulls despite the NOT NULL constraint on t1. There are other constructs such as GROUPING SETS that break the equivalence, too. So you'd need a fairly careful inspection of the view parsetree not only to find which table is referenced, but whether there's something in the view that defeats the deduction you'd like to make. There isn't anything in Postgres right now that makes that type of inference, let alone a way to export it to userland. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
