On 5/23/07, Naz Gassiep <[EMAIL PROTECTED]> wrote:
"*Really* big sites don't ever have referential integrity. Or if the few
spots they do (like with financial transactions) it's implemented on the
application level (via, say, optimistic locking), never the database level."
It's not just the big ones. Try using Ruby on Rails -- and its ORM,
ActiveRecord -- at some point, and you will notice the rampant
ignorance of referential integrity. ActiveRecord bears signs of having
been designed for MySQL.
For example, you need a plugin to add programmatic support for
foreign-key declarations to your schema code, and foreign key
relationships have to be explicitly defined using directives such as
"has_many". The unit test framework assumes it can delete rows in any
order, irrespective of foreign-key references. And so on.
Interestingly, ActiveRecord's support for polymorphic object
associations -- which allow you define a reference to an object in an
arbitrary table -- violates RI *per definition*. There's no support
for setting up the check constraints that would be appropriate for
such attributes. All the more annoying, since such associations are
extremely useful.
Alexander.
---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?
http://www.postgresql.org/docs/faq
