Re: looking for a globally unique row ID

>> Isn't this typically handled with an inheritance (parent-children)
>> setup. MasterDocument has id, subtype and any common columns (create
>> date etc) then dependents use the same id from master to complete the
>> data for a given type. This is really common in ORM tools. Not clear
>> from the description if the operations could be similarly handled
>> (operation id, operation type as master of 17 dependent
>> operationSpecifics; there is also the "Activity Model")
> I do that, but may be I do that badly.
>
> Currently I do have 6 levels of inheritance which partition my
> document-class space. But I cannot see any way to have a unique index
> (unique constraint) to cover all those partitions at once.
>
> This is actually the core of my question: How to make one?

I cannot image a single postgres index covering more than one physical
table. Are you really asking for that? Remember each dependent record
has an entry in the master so the master guarantees a unique set of keys
across all the dependents. Now if you have enough documents you may get
into partitioning but that's a separate issue.
How you model the work done on (or state transition of) those documents
is a yet another design, but at least the work flow model can safely,
consistently refer to the master table.