Re: information_schema and not-null constraints

Vik Fearing <vik(at)postgresfriends(dot)org> writes:
> On 9/6/23 00:14, David G. Johnston wrote:
>> I'm not all that for either A or B since the status quo seems workable.

> Pray tell, how is it workable? The view does not identify a specific
> constraint because we don't obey the rules on one side and we do obey
> the rules on the other side. It is completely useless and unworkable.

What solution do you propose? Starting to enforce the spec's rather
arbitrary requirement that constraint names be unique per-schema is
a complete nonstarter. Changing the set of columns in a spec-defined
view is also a nonstarter, or at least we've always taken it as such.

If you'd like to see some forward progress in this area, maybe you
could lobby the SQL committee to make constraint names unique per-table
not per-schema, and then make the information_schema changes that would
be required to support that.

In general though, the fact that we have any DDL extensions at all
compared to the standard means that there will be Postgres databases
that are not adequately represented by the information_schema views.
I'm not sure it's worth being more outraged about constraint names
than anything else. Or do you also want us to rip out (for starters)
unique indexes on expressions, or unique partial indexes?

regards, tom lane