Postgres Recursive query + group by + join in Django - django

Question

My Requirement is to write a sql query to get the sub-region wise (fault)events count that occurred for the managedobjects. My database is postgres 8.4. Let me explain using the table structure.
My tables in django:
Managedobject:
class Managedobject(models.Model):
name = models.CharField(max_length=200, unique=True)
iscontainer = models.BooleanField(default=False,)
parentkey = models.ForeignKey('self', null=True)
Event Table:
class Event(models.Model):
Name = models.CharField(verbose_name=_('Name'))
foid = models.ForeignKey(Managedobject)
Managedobject Records:
NOC
Chennai
MO_1
MO_2
MO_3
Mumbai
MO_4
MO_5
MO_6
Delhi
Bangalore
IP
Calcutta
Cochin
Events Records:
event1 MO_1
event2 MO_2
event3 MO_3
event4 MO_5
event5 MO_6
Now I need to get the events count for all the sub-regions. For example,
for NOC region:
Chennai - 3
Mumbai - 2
Delhi - 0
Bangalore - 0
So far I am able to get the result in two different queries.
Get the subregions.
select id from managedobject where iscontainer = True and parentkey = 3489
For each of the region (using for loop), get the count as follows:
SELECT count(*)
from event ev
WHERE ev.foid
IN (
WITH RECURSIVE q AS (
SELECT h
FROM managedobject h
WHERE parentkey = 3489
UNION ALL
SELECT hi
FROM q
JOIN managedobject hi
ON hi.parentkey = (q.h).id
)
SELECT (q.h).id FROM q
)
Please help to combine the queries to make it a single query and for getting the top 5 regions. Since the query is difficult in django, I am going for a raw sql query.

Answer 1

I got the query:
WITH RECURSIVE q AS (
SELECT h,
1 AS level,
id AS ckey,
displayname as dname
FROM managedobject h
WHERE parentkey = 3489
and logicalnode=True
UNION ALL
SELECT hi,
q.level + 1 AS level,
ckey,
dname
FROM q
JOIN managedobject hi ON hi.parentkey = (q.h).id
)
SELECT count(ckey) as ccount,
ckey,
dname
FROM q
JOIN event as ev on ev.foid_id = (q.h).id
GROUP BY ckey, dname
ORDER BY ccount DESC
LIMIT 5