Re: pg_depend explained

2011/1/11 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Try reading the code in src/backend/catalog/dependency.c.

I've tried but failed to figure it out anyway. The focus in
dependency.c is to find out dependencies of a given object.
What I want to do is something slighly different.
I need to figure out the order of creation of all objects, not just
the dependencies for a single object.

Basically, I want to do "order by oid", but since you cannot trust the
oid order (like we did in pre-7.3), I need to get the sorted list
using pg_depend somehow.

I guess I could make findDependentObjects() callable from sql and call
it for each and every object, but that's a quite big project, I was
hoping it was possible to do it in plain sql, or at least only by
relying on plpgsql/plperl.

I've implemented tsort() in plperl, but that didn't really help me
much, since you need to jump around in the tree when you encounter
'internal' and 'auto' nodes.

My last resort is to sort by oid, but I really don't want to do that
since it would render the entire solution unreliable and I would never
feel comfortable using it in the production environment.

This is the last component I need in order to complete the work on the
pov-project http://www.github.com/gluefinance/pov

I would highly appreciate your help, I feel a bit lame since I've
spent over two days working on this. It's not difficult if you are
allowed to build specialized queries for each class, but my goal is a
general query only relying on pg_depend.

--
Best regards,

Joel Jacobson
Glue Finance