[openstack-dev] [Keystone]ON DELETE RESTRICT VS ON DELETE CASCADE

Adam Young ayoung at redhat.com
Tue Mar 10 17:08:14 UTC 2015


On 03/10/2015 10:23 AM, Mike Bayer wrote:
> if*that’s*  what you mean, that’s known as a “polymorphic foreign key”, and
> it is not actually a foreign key at all, it is a terrible antipattern started by
> the PHP/Rails community and carried forth by projects like Django.
A) Heh. it is much, much older than that.  SQL Database have been around 
for long enough for these antipatterns to be discovered and rediscovered 
by multiple generations.  I'm aware of the mean by which we cn mitigate 
them.

But that is not what we are doing here.  These are no "parity" issues 
even.  It is distributed data.

User sand Groups are in, not just one LDAP server,  but many.  With 
Federation, the users  will not even be in a system we can enumerate.  
Which is good, we should never have been allowing "list users" in the 
first place.

What the Assignments table is doing is pulling together the User and 
groups from remote systems together with role defintions and project 
definitions in the local database.  The data is not in one database.  It 
is in Many.
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