Tom Lane írta:
Zoltan Boszormenyi <[EMAIL PROTECTED]> writes:
I have two questions about the dependency system.


1. Is there a built-in defense to avoid circular dependencies?

It doesn't have a problem with them, if that's what you mean.

2. If I register dependencies between column, is there a way
    to retrieve all table/column type dependencies for a depender column?

You can scan pg_depend.

What I would like to achieve is to lift the limit that
a GENERATED column cannot reference another one.

I would counsel not doing that, mainly because then you will have to
solve an evaluation-order problem at runtime.

OK.

Point taken. So, just like with SET / DROP IDENTITY,
I should implement SET GENERATED ALWAYS
and DROP GENERATED.

If you think of it as a property of the default expression, then DROP
DEFAULT covers both cases, you don't need DROP GENERATED...

So, I should allow DROP DEFAULT, implement
SET DEFAULT GENERATED ALWAYS AS
and modify the catalog so the GENERATED property
is part of pg_attrdef. What about IDENTITY?
Should it also be part of pg_attrdef? There are two ways
to implement it: have or don't have a notion of it.
The latter would treat GENERATED BY DEFAULT AS IDENTITY
the same as SERIAL.

                        regards, tom lane

--
----------------------------------
Zoltán Böszörményi
Cybertec Geschwinde & Schönig GmbH
http://www.postgresql.at/


---------------------------(end of broadcast)---------------------------
TIP 1: if posting/reading through Usenet, please send an appropriate
      subscribe-nomail command to [EMAIL PROTECTED] so that your
      message can get through to the mailing list cleanly

Reply via email to