On 2011-01-10, Joel Jacobson <joel(at)gluefinance(dot)com> wrote:
> Hi,
>
> Is it safe to assume all objects of a given class can be
> dropped/created, provided all objects of a list of other classes have
> already been dropped/created?
>
> I'm looking at http://developer.postgresql.org/pgdocs/postgres/catalogs.html
>
> For each class, a list of "References" are defined, i.e. other classes
> the given class depend on.
> For instance, is it correct to assume constraints always can be
> dropped, i.e. no other class (nor other constraints) can depend on
> them?
As I unserstand it a references constraint requires a unique
constraint on the referred-to expressiom.
table a (b,c) references d(e,f)
requires
unique (e,f) on table d
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⚂⚃ 100% natural