Re: Implementing pg_dump_sort.c topological sorting in sql/plpgsql/plperl?

Joel Jacobson <joel(at)gluefinance(dot)com> writes:
> It's not possible to use a plain recursive query to do the trick (due
> to 'i' bidirectional dependencies and dependency loops).

Well I came up with that while working on some extension related fun
dependency problems, I guess it could help you:

~:5490=# WITH RECURSIVE depends AS (
select 16385 as nsp, objid, refobjid, array[refobjid] as deps
from pg_depend
where refobjid = 16854 and deptype != 'p'
UNION ALL
select p.nsp, p.objid, d.refobjid, deps || d.refobjid
from pg_depend d JOIN depends p ON d.objid = p.objid
where d.deptype != 'p' and not d.refobjid = any(deps)
)
select * from depends;
nsp | objid | refobjid | deps
-------+-------+----------+--------------------
16385 | 16851 | 16854 | {16854}
16385 | 16852 | 16854 | {16854}
16385 | 16853 | 16854 | {16854}
16385 | 16851 | 2200 | {16854,2200}
16385 | 16852 | 2200 | {16854,2200}
16385 | 16852 | 16851 | {16854,16851}
16385 | 16853 | 2200 | {16854,2200}
16385 | 16852 | 2200 | {16854,16851,2200}
16385 | 16852 | 16851 | {16854,2200,16851}
(9 rows)

Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support